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Biodiesel (methyl esters) has been produced using numerous catalysts to enhance its quality and related productivity. Generally, the raw materials for biodiesel production and its catalysts significantly impact the produced biodiesel's quality. In addition, the heterogeneous catalysts are promising as catalysts in the transesterification for biodiesel production and can be used continuously during this production. In particular, these catalysts are essential for green biodiesel production because of their high activity, thermal stability, and reusability. Hence, several homogeneous and heterogeneous (acidic and alkaline) catalysts for biodiesel production, particularly the naturally derived heterogeneous catalysts, are reviewed in this article. Further, the different heterogeneous catalysts for biodiesel production have been studied extensively as replacements for the respective homogeneous catalyst. Specifically, this replacement is aimed at the simultaneous esterification and transesterification of the nonedible and low-cost biomasses under moderate conditions producing biodiesel. Moreover, this study analyzes biodiesel's impact and long-term performance in various applications. Finally, it also reports the advancements in biodiesel production in terms of the catalysts used in it and its processes to aid further developments in biodiesel production. [ABSTRACT FROM AUTHOR]

In this study, we analyzed the effect of dispersant characteristics on the selective catalytic reduction (SCR) catalyst properties and de-NOx efficiency. For this, we measured the zeta potential and pH value of each dispersant, and compared the thermal properties of the dispersant through TG-DTA analysis. Also, the Py-GC/MS analysis results and the MSDS contents of the product were used to compare the components and molecular weight types of the dispersant. As a result, the higher the zeta potential, pH, and molecular weight of the dispersant, the more improved the dispersibility of the TiO2 slurry. Characteristics such as the rheology, sedimentation, and pH change, were studied to compare the dispersibility of the catalyst slurries, and the dispersion characteristics of the TiO2 slurries were confirmed by TEM. The SCR catalysts prepared varied based on the dispersant added, with the varying factor being the de-NOx efficiency between (250 to 450) °C depending on the dispersibility. The dispersant with the excellent dispersibility gave the highest efficiency of 84% or more at 250°C and 300°C, and the highest de-NOx efficiency of more than 92% at 350°C and 400°C. [ABSTRACT FROM AUTHOR]

Summary: Banner waste contributes to a tremendous amount of plastic waste, which requires a proper treatment method. As catalytic pyrolysis is an effective plastic treatment method, this study explored the effects of Co3O4 catalyst configuration on the characteristics and energy contents of pyrolytic products of banner waste. In situ configuration (feedstock and catalyst in direct contact) provided intimate contact of pyrolysis vapors with the catalyst, which enhanced thermal cracking of the feedstock and its pyrolyzates. This resulted in higher yields of gas and liquid pyrolyzates and a lower yield of solid residue, compared with ex situ configuration (feedstock and catalyst not in direct contact). The Co3O4 catalyst promoted decarboxylation and suppressed decarbonylation. In comparison with in situ configuration, ex situ configuration further enhanced the effects of promoting decarboxylation and suppressing decarbonylation. Wax species (ie, heavy molecules of C>20) were only found in in situ configuration, most likely because, in ex situ configuration, the heavy carbon molecules form coke deposited on the catalyst. Non‐catalytic pyrolysis led to pyrolytic gas with a heating value (14.4 MJ kg−1) that was higher than pyrolytic gases produced in either in situ or ex situ configuration. Using in situ configuration, increased the heating value of pyrolytic liquid (35.4 MJ kg−1) and char (21.3 MJ kg−1), in comparison with using ex situ configuration. This is the first study that examines the impact of catalyst configuration on pyrolysis of banner waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu/CoS@nickel foam (CCSNF) is fabricated by sulfurizing CuCo-LDH on NF. • CCSNF possesses more surface area, current density, and lower charge transfer resistance. • CCSNF ourperforms CuCo-LDH@NF & CuCo 2 O 4 @NF for activating MPS to degrade RB. • RB degradation by CCSNF-activated MPS leads to the significantly lower E a of 26.8 kJ/mol. • CCSNF can be reused to activate MPS for RB degradation over 5 cycles and remains effective. While metal oxides are conventionally proposed for activating monopersulfate (MPS) to degrade refractory contaminants, metal sulfides have recently gained increased attention for MPS activation because these sulfides exhibit more reactive redox characteristics to enhance the catalytic activation of MPS. The present study attempts to develop a novel material comprised of metal sulfides with 3D hierarchical nanostructures to activate MPS. Specifically, a 3D hierarchically structured catalyst was fabricated by growing CuCo-layered double hydroxide (LDH) on nickel foam (NF), followed by direct sulfurization, affording Cu/CoS@NF (CCSNF). CCSNF could exhibit a unique morphology of floral bunches comprised of nano-needles, residing on the NF surfaces. Compared with its precursor, CuCo-LDH@NF, oxide analogue, and CuCo 2 O 4 @NF, CCSNF possessed superior physical and chemical properties, including larger surface area and pore volume, higher current density, and lower charge transfer resistance. These features render CCSNF a much more effective catalyst than CuCo-LDH@NF and CuCo 2 O 4 @NF for activating MPS to degrade Rhodamine B (RB). In particular, RB degradation by CCSNF-activated MPS required an activation energy only 26.8 kJ/mol, which is much lower than the reported values. The activation mechanism and degradation pathway of RB degradation by CCSNF-activated MPS were investigated and validated through experimental evidences and density function theory calculations. [ABSTRACT FROM AUTHOR]

Summary: Catalytic effects in fast pyrolysis of low‐rank coal and coal tar conversion were investigated in a two‐stage fixed‐bed reactor over HZSM‐5 zeolite and Mg/HZSM‐5. Mg/HZSM‐5 caused the lower total tar yield and the higher non‐condensable gas yield but the fraction of light tar (boiling point below 360°C) increased to allow a slightly higher total yield of light tar. It also exhibited good catalytic activity and increased the species of light tar than HZSM‐5 zeolite. The light tar fraction was increased from 45 to 74.6 wt% than without catalyst (66%) at the pyrolysis temperature of 600°C. Ex‐situ catalytic fast pyrolysis over Mg/HZSM‐5 also lowered the contents of element N and S in the resulting coal tars by 29% and 15% respectively. The corresponding increase in the content of element H and molar ratio of H to C of the resulting coal tars was reported as 17% and 13% respectively. The addition of Mg into HZSM‐5 increased the ability of the catalyst for inhibiting coke deposition. [ABSTRACT FROM AUTHOR]

Summary: As the global vehicle demand increases, the significance of waste materials generated from end‐of‐life‐vehicles (ELVs) becomes more severe. However, the heterogeneity of most components of vehicles made them difficult to be recycled. In this study, a sustainable valorization platform for the vehicle wastes was suggested via pyrolysis process. As a case study, bumper waste was used as a feedstock material. Prior to the thermo‐chemical process of bumper waste, multiple analytical tools were employed to identify and quantify the chemical constituents of the bumper waste. Because the bumper consists of mainly polypropylene (PP), pyrolysis of bumper produced hydrogen and different types of hydrocarbons (HCs), and the product distribution was highly contingent on pyrolysis setups and operating conditions. One‐step pyrolysis of PP at 600°C resulted in C8‐46 aliphatic HCs, while two‐step pyrolysis converted the long‐chain HCs into C7‐8 aromatic compounds in line with H2 production. During catalytic pyrolysis over Co and Ni catalysts, the dehydrogenation of HCs led to rapid H2 generation with coke formation on the catalysts. When CO2 was used as a reactive gas medium, additional CO production and suppression of coke formation were shown through gas‐phase reactions between CO2 and volatile HCs evolved from thermolysis of PP. The alteration of H2/CO ratios (>15 to 0.7) of output gas also was achieved, controlling the N2/CO purge gas ratios during catalytic pyrolysis. Therefore, CO2‐assisted pyrolysis can be a considerable valorization platform of vehicle waste materials and CO2 by converting them into energy‐intensive products. [ABSTRACT FROM AUTHOR]

Oxidation of o-xylene was performed using alkaline battery-based catalyst doped with platinum to investigate the properties and activities. O-xylene was selected as the model of volatile organic compound (VOC) in this work. Physicochemical properties of the selected catalysts were characterized by FE/TEM (field emission transmission electron microscopy), BET (Brunauer-Emmett-Teller) analysis, XRD (X-ray powder diffraction), SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectroscopy), and H2-TPR (hydrogen temperature programmed reduction). Major elements of the spent alkaline battery-based catalyst treated with sulfuric acid solution [SAB (400) catalyst] were manganese, zinc, iron, oxygen, carbon, chlorine, aluminum, sodium, silicon, and potassium. Increasing the doping amount of platinum on SAB (400) catalyst from 0.1 to 1 wt% increased particle size of platinum and lowered the temperature of TPR (TTP) for SAB (400) catalyst. Better redox properties were achieved with an increase in the o-xylene conversion according to the doping amount of platinum. When GHSV (gas hourly space velocity) was 40,000 h−1, o-xylene was oxidized completely over SAB (400) catalyst and 1.0 wt% Pt/SAB(400) catalyst at temperatures of 400 °C and 280 °C, respectively. [ABSTRACT FROM AUTHOR]

To evaluate waste alkaline battery (WB) as a catalyst for deep oxidation of toluene and o-xylene, we investigated how calcination temperature influenced the catalytic activity of WB-based catalyst for catalyst preparation. Physicochemical properties of WB-based catalysts were characterized by BET (Brunauer Emmett Teller) analysis, XRD (X-ray diffraction), SEM/EDX (scanning electron microscope/energy dispersive X-ray), TGA/DTA (thermo gravimetric analysis/differential thermal analysis), and H2-TPR (hydrogen temperature programmed reduction). Major elements of WB-based catalysts were carbon, manganese, zinc, and iron. The catalytic activity of WB-based catalyst was significantly influenced by calcination temperatures ranging from 300 °C–600°C. An increase calcination temperature resulted in a significant decrease in the BET surface area and concentrations of surface carbon and chlorine of the WB-based catalyst, while levels of other components increased. The average pore diameter of the WB-based catalyst calcined at 400 °C (WB (400) catalyst) was the smallest. The concentrations of manganese and iron in WB (400) catalyst were the highest, while those of manganese and iron in the WB-based catalyst calcined at 300 °C (WB (300) catalyst) were the lowest. Therefore, a good performance of WB (400) catalyst was likely due to its higher concentrations of manganese and iron and smaller pore size. When GHSV (gas hourly space velocity) was 40,000 h−1, toluene and o-xylene were completely oxidized on WB (400) catalyst at 430 °C and 440 °C, respectively. [ABSTRACT FROM AUTHOR]

Catalytic hydrodeoxygenation (HDO) of anisole, a methoxy-rich lignin-derived bio-oil model compound, was carried out over a series of Ni-containing (5, 10, 20, and 30 wt%) catalysts with commercial silica and ordered mesoporous silica SBA-15 as support. Both supports and catalysts were characterized by N2 adsorption-desorption isotherms, X-ray diffraction, CO chemisorption, and transmission electron microscopy (TEM). Catalytic reaction was performed at 250 °C and 10 bar H2 pressure. Depending on the catalyst support used and the content of active metal, the catalytic activity and product distribution changed drastically. Increase of the nickel loading resulted in increased anisole conversion and C6 hydrocarbon (benzene and cyclohexane) yield. However, loading more Ni than 20 wt% resulted in a decrease of both conversion and C6 yield due to agglomeration of Ni particles. In addition, Ni/SBA-15 samples exhibited much stronger catalytic activity and selectivity toward C6 hydrocarbon products compared with Ni/silica catalysts. The differences in catalytic activity among these catalysts can be attributed to the effect of the pore size and pore structure of mesoporous SBA-15. SBA-15 can accommodate more Ni species inside channels than conventional silica due to its high pore volume with uniform pore structure, leading to high HDO catalytic activity. [ABSTRACT FROM AUTHOR]

In this study, the oligomerization of a butene mixture composed of 1-butene, cis-2-butene and trans-2-butene over several types of zeolites in a fixed-bed catalytic reactor at an elevated pressure was studied to produce hydrocarbons in the jet fuel range (C8-C16). Three types of zeolites, HZSM-5, Hβ and HY, were compared to evaluate the performance during the synthesis of jet fuel via the oligomerization of the aforementioned butene mixture. Compared to HY and Hβ, HZSM-5 showed a very stable butene conversion rate with high selectivity to jet-fuel-range hydrocarbon, which could be attributed to high resistance to coke resulting from the pore structure. HZSM-5 (50) shows the best quantitative conversion performance and yield for jet fuel for a time-on-stream of up to 6 h. It was also noted that the branched-to-linear hydrocarbon ratio reached 8.7 over the HZSM-5 (50) catalyst, which is beneficial to improve the cold properties of jet fuel. The present study reveals that HZSM-5 (50) is a potential catalyst for jet fuel synthesis through the oligomerization of butene mixture, exhibiting high stability and a high yield. [ABSTRACT FROM AUTHOR]

In this study, a process for producing hydrogen from liquid hydrocarbons by applying plasma is proposed. Toluene was decomposed by discharging a pulse-type plasma into liquid toluene directly. The changes in the rate of hydrogen production and reaction characteristics owing to injecting a perovskite catalyst were also investigated. A high hydrogen production rate of approximately 130 NL/h·g was obtained from the liquid–phase plasma reaction of toluene using the BiFeO 3 catalyst. The investigation into the reaction characteristics based on the plasma generation conditions indicated that the reaction was mainly affected by the plasma voltage. When titanium dioxide and perovskite (SrTiO 3 , BiFeO 3) photocatalysts were applied to this reaction, the reaction activities also varied depending on the light-absorption capacity of the catalysts. The highest hydrogen evolution rate was obtained using the BiFeO 3 catalyst, which absorbs visible light as well as UV light, compared with the TiO 2 photocatalyst, which absorbs only UV light. Because the plasma emission from toluene is predominantly in the visible region, the reaction activity was also determined to be the highest for the BiFeO 3 catalyst. The BiFeO 3 absorbs visible light up to about 550 nm, and it has a small bandgap energy of about 2.15 eV. This led to high photocatalytic degradation activity in visible light generated by plasma discharge in toluene. The carbon obtained had a particle size of less than 20 nm and purity of approximately 99%. • Photocatalytic decomposition of liquid toluene was conducted by liquid plasma on perovskite catalysts. • Pure hydrogen gas and carbon particles were simultaneously produced in the decomposition reaction. • BiFeO 3 perovskite exhibited a high hydrogen production rate due to its excellent visible light activity. • The produced carbon particles were small and uniform in nano size and had a large surface area. • The hydrogen production was greatly enhanced up to 130 NL/h·g in this cracking process. [ABSTRACT FROM AUTHOR]

This study investigated catalytic ozone oxidation using a sawdust char (SDW) catalyst to remove hazardous toluene emitted from the chemical industry. The catalyst properties were analyzed by proximate, ultimate, nitrogen adsorption-desorption isotherms, Fourier-transform infrared, and X-ray photoelectron spectroscopy analyses. In addition, hydrogen-temperature programmed reduction experiments were conducted to analyze the catalyst properties. The specific area and formation of micropores of SDC were improved by applying KOH treatment. MnOx/SDC-K3 exhibited a higher toluene removal efficiency of 89.7% after 100 min than MnOx supported on activated carbon (MnOx/AC) with a removal efficiency of 6.6%. The higher (O ads (adsorbed oxygen)+O v (vacancy oxygen))/O L (lattice oxygen) and Mn3+/Mn4+ ratios of MnOx/SDC-K3 than those of MnOx/AC seemed to be important for the catalytic oxidation of toluene. [ABSTRACT FROM AUTHOR]

Highly dispersed MoO3 on SiMCM-41 was applied to the dehydration of 2-butanol. MoO3 / MCM-41 catalysts were prepared using a modified atomic layer deposition method. The structural characteristics of MoO3 supported on SiMCM-41 were examined by inductively coupled plasma spectrometry, nitrogen adsorption, X-ray photoelectron spectroscopy, and X-ray diffraction. The textural characteristics of SiMCM-41 were retained after loading with MoO3 . Ammonia temperature-programmed desorption and Fourier transformation infrared spectroscopy of adsorbed pyridine showed that Lewis acid sites were formed on the MoO3 / MCM-41 catalysts. Among the MoO3 / MCM-41 catalysts, the MoO3 (16.4 wt %)/ MCM-41 catalyst showed the highest catalytic activity for butene synthesis from 2-butanol dehydration due to the largest number of acid sites. [ABSTRACT FROM AUTHOR]

Dibenzothiophene sulfone, one of the products of the oxidative desulfurization of heavy oil, can be utilized through catalytic cracking. The object of the present study is to provide Cs/MCM-41 catalysts for the removal of sulfur dioxide from dibenzothiophene sulfone. Cesium oxide was deposited via an impregnation method on MCM-41, and the catalytic performances of the samples were investigated during the deoxydesulfurization of dibenzothiophene sulfone to biphenyl and sulfur dioxide gas. The influence of cesium loading on the basic properties of MCM-41 was estimated by the temperature-programmed desorption of carbon dioxide. The dibenzothiophene sulfone conversions of the MCM-41, Cs(1 wt%)/MCM-41, Cs(3 wt%)/MCM-41 and Cs(10 wt%)/MCM-41 catalysts were 38.5, 52.1, 72.4 and 40.9%, respectively, which implies that the Cs(3 wt%)/MCM-41 catalyst has the highest activity. This result agrees with the finding of the basicity enhancement of MCM-41 with the addition of cesium, in which Cs(3 wt%)/MCM-41 exhibited a maximum number of basic sites. [ABSTRACT FROM AUTHOR]

This study examined the H2 production characteristics from a decomposition reaction using liquid-phase plasma with a bismuth ferrite catalyst. The catalyst was prepared using a sol–gel reaction method. The physicochemical and optical properties of bismuth ferrite were analyzed. H2 production was carried out from a distilled water and aqueous methanol solution by direct irradiation via liquid-phase plasma. The catalyst absorbed visible-light over 610 nm. The measured bandgap of the bismuth ferrite was approximately 2.0 eV. The liquid-phase plasma emitted UV and visible-light simultaneously according to optical emission spectrometry. Bismuth ferrite induced a higher H2 production rate than the TiO2 photocatalyst because it responds to both UV and visible light generated from the liquid-phase plasma. [ABSTRACT FROM AUTHOR]

The applicability of ferrierite to the catalytic degradation of polyethylenes, such as high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), and the effect of its acidity have been investigated using a thermogravimetric analyzer and batch reactor. Quantitative analyses of the products were also carried out using GC-MS and GC-FID. The apparent activation energy of the catalytic degradation of polyethylene was significantly lowered by the addition of the catalysts. Ferrierite, with a low SiO2/Al2O3 ratio, exhibited pronounced selectivity for the production of valuable olefins and excellent resistance to coke formation. All ferrierites generated mainly C6–C10 hydrocarbons, and seemed to have the catalytic stability in the degradation of polyethylene. [ABSTRACT FROM AUTHOR]

Noble (Pt, Pd) and transition metals (Mn, Cu) were employed as coupling catalysts to evaluate the toluene (1500 ppm C of initial concentration) removal efficiencies in the electron beam (EB)–catalyst coupling system. The toluene removal efficiency was 60.1% in the EB-only system at a dose of 8.7 kGy. In the presence of the metal catalysts (Pt, Pd, Cu and Mn), the removal efficiency was enhanced by 37, 33, 6 and 22%, respectively, compared to that of EB-only treatment. It was found that the selectivity to CO2 with Pt and Pd coupling were relatively higher than those of Cu and Mn. Especially the CO2 selectivity of EB–Pt coupling was significantly high at a relatively low absorbed dose. The removal efficiencies were compared for loading of catalyst and there was no significant difference among 0.1, 0.5 and 1.0 wt%. [ABSTRACT FROM AUTHOR]

• Recycling of spent alkaline batteries was studied. • Spent alkaline batteries were tested as a catalyst for total oxidation of VOCs. • The effect of acid treatment on SB catalyst was investigated. A spent alkaline battery-based (SB) catalyst was prepared from the black mass of a spent alkaline battery to determine the potential of recycling spent alkaline batteries as catalysts for the total oxidation of hydrocarbons. Five different acids (H 2 SO 4 , HNO 3 , C 2 H 2 O 4 , HCl, and H 3 PO 4) were used to examine the effect of acid treatment on catalytic activity during catalyst preparation. Hexane, benzene, toluene, and o-xylene (HBTX) were adopted as the VOCs for experiments. The properties of the prepared catalysts were studied using ICP/OES, BET, XRD, ATR/FTIR, TGA, SEM, and H 2 -TPR analyses. The results showed that acid treatment significantly influenced the activity of the SB (400) catalyst, with the type of acid also found to greatly influence the activity of the catalyst. The order of activity according to the type of acid was H 2 SO 4 > HNO 3 > C 2 H 2 O 4 > HCl > H 3 PO 4 > none. Good performance of an acid-treated SB catalyst was associated with high concentrations of manganese and iron and a large BET surface area. In addition, the sequence in which the TPR peaks appeared at low temperatures according to each acid treatment was consistent with that of catalyst activity. [ABSTRACT FROM AUTHOR]

• A biomass waste and CO 2 to syngas conversion platform was constructed. • Catalytic pyrolysis promoted conversion of Styrax japonicus to syngas under CO 2 /N 2. • CO 2 suppressed coke formation on Ni catalyst. • Synergistic effects of Ni catalyst and CO 2 substantially improved syngas generation. This work laid emphasis on catalytic pyrolysis of Styrax japonicus to construct a biomass-to-energy conversion platform. CO 2 was particularly chosen to enhance the catalytic pyrolysis of the biomass waste, in reference to N 2 -purged pyrolysis. The specific roles of CO 2 on pyrolysis of S. japonicus in line with synergistic effect of Ni-based catalysts was investigated. It was shown that CO 2 played as an oxidant for CO formation via homogeneous gas phase reaction of CO 2 with volatile organic carbons (VOCs) liberated from the thermolysis of S. japonicus. Ni/SiO 2 catalyst expedited dehydrogenation (DH) of the VOCs, resulting in significant H 2 generation and alteration of aromaticity in VOCs. Each CO 2 and Ni catalyst independently enhanced CO and H 2 formation, respectively, and their synergistic effects were shown at ≥ 600 °C. Coke deposition on the Ni/SiO 2 catalyst was confirmed after catalytic pyrolysis, while the suppression of coke formation on the catalyst surface was achieved under the CO 2 environment. [ABSTRACT FROM AUTHOR]

The thermal and catalytic pyrolysis of two kinds of Tetra Pak waste (TP-1 and TP-2) over three different acidic catalysts—HZSM-5(SiO2/Al2O3, 30), HBeta (38), and Al-MCM-41(20)—were investigated in this study. Tetra Pak (TP) wastes consist of composite material comprising kraft paper, polyethylene (PE) film, and aluminum foil. Thermal decomposition behaviors during the pyrolysis of TPs were monitored using a thermogravimetric (TG) analyzer and tandem micro reactor-gas chromatography/mass spectrometry (TMR-GC/MS). Neither the interaction between the non-catalytic pyrolysis intermediates of kraft paper and PE, nor the effect of aluminum foil have been monitored during the non-catalytic TG analysis of TPs. The maximum decomposition temperatures of PE in TP-1 shifted from 465 °C to 432 °C by HBeta(38), 439 °C by HZSM-5(30), and 449 °C by Al-MCM-41(20), respectively. The results of the TMR-GC/MS analysis indicate that the non-catalytic pyrolysis of TPs results in the formation of large amounts of furans and heavy hydrocarbons and they are converted efficiently to aromatic hydrocarbons over the acidic catalysts. Among the three catalysts, HZSM-5(30) produced the largest amount of aromatic hydrocarbons, followed by HBeta(38) and Al-MCM-41(20) owing to their different acidity and pore size. Compared to TP-1, TP-2 produced a larger amount of aromatic hydrocarbons via catalytic pyrolysis because of its relatively larger PE content. The synergistic formation of aromatic hydrocarbons was also enhanced during the catalytic pyrolysis of TPs due to the effective role of PE as hydrogen donor to kraft paper. In terms of their catalytic effectiveness, HZSM-5(30) had a longer lifetime than HBeta(38). [ABSTRACT FROM AUTHOR]

The in-situ catalytic fast pyrolysis of pinecone over HY catalysts, HY(30; SiO2/Al2O3), HY(60), and 1% Ni/HY(30), was studied by TGA and Py-GC/MS. Thermal and catalytic TGA indicated that the main decomposition temperature region of pinecone, from 200 to 400 °C, was not changed using HY catalysts. On the other hand, the DTG peak heights were differentiated by the additional use of HY catalysts. Py-GC/MS analysis showed that the efficient conversion of phenols and other oxygenates formed from the pyrolysis of pinecone to aromatic hydrocarbons could be achieved using HY catalysts. Of the HY catalysts assessed, HY(30), showed higher efficiency in the production of aromatic hydrocarbons than HY(60) because of its higher acidity. The aromatic hydrocarbon production was increased further by increasing the pyrolysis temperature from 500 to 600 °C and increasing the amount of catalyst due to the enhanced cracking ability and overall acidity. The use of 1% Ni/HY(30) also increased the amount of monoaromatic hydrocarbons compared to the use of HY(30) due to the additional role of Ni in enhancing the deoxygenation and aromatization of reaction intermediates. [ABSTRACT FROM AUTHOR]

[Display omitted] • Supported rhenium nanoparticles are studied for the hydrodeoxygenation (HDO) of phenols. • Metallic rhenium is an active site for the dehydroxlyation of phenols to cyclohexane. • Rhenium supported on SiO 2 is easily leached and sintered under liquid-phase HDO conditions. • Re/TiO 2 is leaching-resistant while exhibiting high activity and selectivity to cyclohexane. • Rhenium on mesoporous TiO 2 demonstrated ∼93% yield of cyclohexane at 553 K within 3 h. Despite the recognized efficacy of rhenium (oxide) for promoting hydrogenolysis of the C O bond of biomass-derived oxygenates when combined with a hydrogenation metal such as Pd or Ru, the hydrogenation function of rhenium itself is relatively unexplored. Herein, we investigated the activity and selectivity of rhenium nanoparticles supported on various metal oxides for the hydrodeoxygenation of guaiacol, i.e., 2-methoxyphenol. Catalytic experiments performed at 280 °C and 20 bar H 2 in a batch reactor revealed that rhenium itself adequately catalyzes the demethoxylation and dehydroxylation of guaiacol, producing completely deoxygenated products of cyclohexane/benzene. The reduced and unreduced rhenium catalysts (Re vs. ReO x) exhibited similar catalytic activity, and both bulk rhenium oxide (ReO 3 and Re 2 O 7) and supported rhenium oxide, i.e., ReO x /SiO 2 , were completely reduced to metallic rhenium after the reaction, suggesting that metallic rhenium is mainly responsible for the hydrogenolysis of guaiacol. Among the catalysts tested, Re/SiO 2 exhibited the highest guaiacol conversion (98%) and the highest selectivity for fully deoxygenated cyclohexane (58%), followed by TiO 2 , Al 2 O 3 , ZrO 2 , and CeO 2. The catalytic activity was generally correlated with the rhenium dispersion as measured by transmission electron microscopy and CO-chemisorption. Despite its high activity, sintering and leaching of rhenium occurred for SiO 2 support, whereas the second most active TiO 2 -supported rhenium catalyst was leaching-resistant. Using Re/TiO 2 as a benchmark catalyst, the effects of the rhenium loading, the mesoporosity of TiO 2 , and reaction conditions on the conversion of guaiacol were further explored. [ABSTRACT FROM AUTHOR]

Platinum catalysts loaded on a hybrid support, composed of HZSM-48 and pseudoboehmite, were applied to the synthesis of benzene through methylcyclopentane (MCP) reforming in order to investigate the effect of the addition of pseudoboehmite to Pt/HZSM-48 for ring-enlargement reaction. A total of 0.5 wt% of platinum was impregnated on the hybrid support by using the incipient wetness method. Catalyst characterization was performed with nitrogen sorption, X-ray diffraction, temperature-programmed desorption of NH3, and infrared spectroscopy of adsorbed pyridine. It was found that mesoporous structures were well-developed in Pt/(HZSM-48 + pseudoboehmite) catalyst as a result of the pseudoboehmite addition, of which the average pore size was in the range of 7–8 nm. The presence of pseudoboehmite in the catalyst increases the total amount of acid sites and weakens the acid strength, compared with those of the Pt/HZSM-48 catalyst. Lewis acid sites were more abundant than Brönsted acid sites over the Pt/(HZSM-48+pseudoboehmite) catalysts. It was found that selectivity to the ring-enlargement reaction is dominant over selectivity to the ring-opening reaction over the Pt/(HZSM-48 + pseudoboehmite) catalysts. The benzene yield over Pt/(HZSM-48 + pseudoboehmite, 1:1) catalyst reached 65.1% at 450 °C and 0.3 h−1. As well as being influenced by the mesoporous structure, the higher activity and selectivity in MCP reforming was also determined by appropriate acidity of the Pt/(HZSM-48 + pseudoboehmite) catalysts. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of a synthesis procedure of Sr hexaaluminate on catalytic performance during the decomposition of ionic liquid monopropellants based on ammonium dinitramide (ADN) and hydroxyl ammonium nitrate (HAN). Sr hexaaluminates were prepared via both coprecipitation and a sol–gel process. The surface area of hexaaluminate synthesized via the coprecipitation method was higher than that of hexaaluminate synthesized by the sol–gel process, and calcined at the same temperature of 1200 °C or more. This is because of the sintering of α-Al2O3 on the hexaaluminate synthesized via the sol–gel process, which could not be observed on the catalysts synthesized via the coprecipitation method. The hexaaluminate synthesized via coprecipitation showed a lower decomposition onset temperature during the decomposition of ADN- and HAN-based liquid monopropellants in comparison with the catalysts synthesized via the sol–gel process, and calcined at the same temperature of 1200 °C or more. This is attributed to the differences in the Mn3+ concentration and the surface area between the two hexaaluminates. Consequently, the hexaaluminate synthesized via coprecipitation which calcined above 1200 °C showed high activity during the decomposition of energetic ionic liquid monopropellants compared with the hexaaluminate synthesized via the sol–gel process. [ABSTRACT FROM AUTHOR]

This study examined the effects of Ni loading on different types of alumina (γ-Al 2 O 3 , mesoporous Al 2 O 3 , 13 nm-sized Al 2 O 3 , and <50 nm-sized Al 2 O 3) for high-density polyethylene gasification for enhanced hydrogen generation. The catalytic activity of Ni loaded alumina was observed in the order of 13 nm-sized Al 2 O 3 > mesoporous Al 2 O 3 > (<50 nm-sized Al 2 O 3) > γ-Al 2 O 3 for the gas yield and γ-Al 2 O 3 > (<50 nm Al 2 O 3) > mesoporous Al 2 O 3 > 13 nm Al 2 O 3 for the oil yield, respectively. In addition, the production of hydrogen from Ni loaded alumina showed an increasing trend in the order of (<50 nm-sized Al 2 O 3) > γ-Al 2 O 3 > 13 nm-sized Al 2 O 3.> mesoporous Al 2 O 3. In contrast, CO showed the trend as Ni/mesoporous Al 2 O 3 > Ni/13 nm-sized Al 2 O 3 > Ni/γ-Al 2 O 3 > (Ni/<50 nm Al 2 O 3). The highest level of hydrogen production from the Ni/<50 nm-sized Al 2 O 3 catalyst might be because of its highest Ni dispersion and surface area. The use of Ni-loaded nm-sized alumina could be an excellent method for increased hydrogen production compared to other types of alumina available. • 4 different Ni/alumina catalysts were applied to HDPE gasification. • γ-Al 2 O 3 , mesoporous Al 2 O 3 , 13 nm-sized Al 2 O 3 , and (<50 nm-sized Al 2 O 3) were used. • The highest level of hydrogen was produced from the Ni/<50 nm-sized Al 2 O 3 catalyst. • Ni/<50 nm-sized Al 2 O 3 catalyst showed highest Ni dispersion and surface area. [ABSTRACT FROM AUTHOR]

• Recent catalytic pyrolysis making bio-oil with a high content of aromatics is discussed. • Zeolites are most widely used for microalgae pyrolysis of to produce high-quality bio-oil. • Challenges and future research in catalytic pyrolysis of microalgae are suggested. The catalytic pyrolysis of microalgae offers a strategic means of increasing the value of pyrogenic products. Microalgae are a promising pyrolysis feedstock. This review summarizes the state-of-the-art catalytic pyrolysis processes to form bio-oil with a high proportion of aromatic compounds. The focus is on the current knowledge of the mechanisms to form aromatic hydrocarbon species from the catalytic pyrolysis of microalgae. In addition, that the effects of the reaction conditions and catalyst selection on the yield and composition of microalgal bio-oil are reviewed. The information shows that the catalyst and feedstock properties are closely associated with the formation of desired aromatic compounds. In addition, this review defines the technical challenges that need to be overcome and suggests future research for the further development of catalytic pyrolysis technologies for the production of aromatics from microalgae. [ABSTRACT FROM AUTHOR]

• Selective production of terephthalate from FDCA ester over heteropolyacids. • Silica-supported HPW is significantly more active than other supported HPAs. • Strong Brønsted acidity is a key to improving the selectivity toward terephthalate. • Terephthalate yield of ˜60% can be achieved by 25%-HPW/SiO 2. The Diels-Alder reaction of biomass-derived dimethyl 2,5-furandicarboxylate (DMFDC) with ethylene followed by dehydrative aromatization is a sustainable route for the production of terephthalic acid, a monomer used for the synthesis of polyethylene terephthalate (PET). In this work, a series of heteropolyacid (HPA) catalysts with different supports, in this case SiO 2 , TiO 2 and ZrO 2 , and hetero-addenda atoms, here phosphotungstic acid (HPW), silicotungstic acid (HSiW) and phosphomolybdic acid (HPMo), were used as catalysts, and their structure-activity correlation in the conversion of DMFDC to terephthalate was examined based on the density and strength of the acid sites. Characterization by XRD and Raman indicated that the Keggin structures of HPAs were well preserved on the SiO 2 support compared to other supports, resulting in strong Brønsted acidity. The silica-supported HPW and HSiW catalysts exhibited significantly higher activity for terephthalate production than other supports and HPMo catalysts, but their activity were not correlated with the total acidity as measured by NH 3 -TPD. In contrast, the catalyst acid strength, as determined by the NH 3 desorption temperature, decreased in the order HPW/SiO 2 > HSiW/SiO 2 >> HPW/ZrO 2 > HPW/TiO 2 > HPMo/SiO 2 and was well correlated with the turnover rate for terephthalate production, suggesting that the higher activity of HPW/SiO 2 is at least partly due to its stronger Brønsted acidity and that promoting the dehydration step of this reaction is a key to improving the selectivity to terephthalate. The effects of reaction conditions, in this case the acid loading amount, solvent used, temperature, and time, were also investigated with the most active silica-supported HPW catalysts to optimize the terephthalate yield. The 25%-HPW/SiO 2 catalyst demonstrated a remarkable terephthalate yield of ∼60% with almost complete conversion under the optimum condition. [ABSTRACT FROM AUTHOR]

The catalytic gasification of sewage sludge was explored using different catalyst particle sizes, bed temperatures, and gasifying agents. Activated carbon and sawdust biochar were used as catalysts in this study. The effects of the porosity of activated carbon on tar adsorption and cracking, and biochar containing alkali and alkaline earth metallic species (AAEMs), which can enhance gasification reactions, were investigated under different conditions. A catalyst bed temperature of 800 °C and particle size of 0.5–1.7 mm showed optimum conditions for increasing H 2 and CO content and decrease CO 2 fraction; however, a higher solid residue (∼38 wt%) was also observed due to the high ash content in sewage sludge. Furthermore, the introduction of steam had a positive effect on the H 2 increment, owing to the presence of inherent AAEMs in the biochar, promoting water gas shift and hydrocarbon steam reforming reactions. The results of this study provide effective measures for using activated carbon and affordable biochar to enhance H 2 production with a parametric effect on the catalyst bed. [Display omitted] • Sewage Sludge gasification was performed over activated carbon and biochar. • Effect of catalysts bed particle size and temperature was investigated. • Particle size of 0.5–1.7 mm and temperature of 800 °C was considered optimum for H 2. • Biochar showed significant water gas shift activity compared to activated carbon. • The presence of AAEMs in biochar can enhance H 2 generation. [ABSTRACT FROM AUTHOR]

Red mud (RM) was assessed as a catalyst for the complete oxidation of volatile organic compounds (VOCs). The catalytic activity of RM was influenced by an acid treatment and the calcination temperature. Acid-treated RM (HRM) catalysts with a platinum loading (Pt/HRM) were prepared using a conventional impregnation method. Platinum catalysts supported on γ-Al 2 O 3 (Pt/Al) were prepared for comparison. The physicochemical properties of the RM, HRM and Pt/HRM catalysts were characterized by BET analysis, ICP-AES, H 2 -TPD, XRD, FTIR, SEM, and FE-TEM. The acid treatment increased the BET surface area of the RM significantly, resulting in an increase in catalytic activity. Increasing the calcination temperature from 400 °C to 600 °C caused a decrease in its catalytic activity. Increasing the platinum loading on HRM(400) from 0.1 wt.% to 1 wt.% led to an increase in the toluene conversion, which was attributed to the better redox properties. The catalytic activities of the Pt/HRM(400) catalysts were superior to those of the Pt/Al catalysts. Benzene, toluene, o-xylene, and hexane were oxidized completely over the 1 wt.% Pt/HRM(400) catalyst at reaction temperatures less than 280 °C. The presence of water vapor in the feed had a negative effect on the activity of the 1 wt.% Pt/HRM(400) catalyst. [ABSTRACT FROM AUTHOR]

Pyrolysis of non-recycled municipal plastic waste has the potential to mitigate the plastic waste crisis and to produce transport fuels (diesel or hydrogen), as compared with the conventional methods such as incineration or landfilling that have potential adverse environmental consequences. Transport fuel production from non-recycled municipal plastic waste contributes to the transition to more sustainable waste management. However, little is known about the influences of system scales and end product selection on the carbon footprints of the plastic waste treatment. Here, we applied the approach of life cycle assessment to compare the carbon-saving potential of centralized, large-scale and decentralized, small-scale pyrolysis systems producing diesel and hydrogen in the United Kingdom. It is shown that centralized systems had a lower global warming potential results than decentralized systems despite their greater transportation distances. The global warming potentials of diesel production for centralized and decentralized systems were 801 and 1345 kg CO 2 -eq. per tonne of non-recycled municipal plastic waste, respectively, whilst hydrogen production had much higher global warming potentials which are 7110 and 7990 kg CO 2 -eq per tonne of non-recycled municipal plastic waste, respectively. In hydrogen-producing systems, crude carbon nanotubes are also produced, and the purification process of carbon nanotubes requires significant material resource (hydrochloric acid and deionized water) inputs, resulting in high Scope 2 and 3 emissions. Also, it is worth noting that the global warming potential related to the Scope 1 emissions for the diesel-producing systems exceeds 80%, whereas the hydrogen-producing systems yield opposite results. The end use of diesel produced has a greater carbon footprint than the end use of hydrogen. The carbon saving from the displacement of fossil hydrogen was two times higher than that from diesel displacement. Decentralized, small-scale hydrogen production from plastic waste had the highest global warming potential among all as the conversion process of municipal plastic waste to hydrogen and carbon nanotubes for small-scale systems is more energy and resource intensive. Sensitivity analysis showed that various factors, such as feedstock composition and the heating energy consumption in the conversion process, had less influence on the global warming potential of centralized systems as compared to decentralized systems. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Acid-treated catalysts were applied for coffee waste bio-oil esterification. • The use of Ti-SO 4 obtained the highest acid conversion and esters generation. • Compared to H 3 PO 4 and HCl, using H 2 SO 4 showed a better effect on TiO 2 treatment. • Increasing the temperature and C/F ration enhanced esters production. • A higher yield of esters was obtained from the reaction in ethanol than methanol. Catalytic esterification of acid-rich coffee waste-derived bio-oil was performed using sulfonated metal oxide catalysts (Al 2 O 3 , MgO, ZrO 2 , and TiO 2) and ethanol to produce fatty acid alkyl esters. The potential of the sulfonated catalysts for esterification decreased in the following order: Ti-SO 4 > Zr-SO 4 > Al-SO 4 > Mg-SO 4. Particularly, Ti-SO 4 and Zr-SO 4 resulted in 91.2 % (peak area %) and 85.2 % esters, respectively. This is attributed to the contributions of well-dispersed Brønsted acid sites created by –SO 3 H functional groups, additional Lewis acid sites formed by Ti and Zr oxides, and their appropriate pore size. Compared with HCl and H 3 PO 4 , the use of H 2 SO 4 for TiO 2 treatment significantly enhanced ester formation. When using Ti-SO 4 , increasing the catalyst-to-feedstock ratio (1/2 ∼ 1/10) significantly increased the esters' selectivity (38.7 %∼94.7 %). Ethanol utilization caused a superior selectivity for esters than methanol, while the increasing temperature favored ester production. This study proposes an eco-friendly and practical method for biodiesel generation. [ABSTRACT FROM AUTHOR]

The study explored the catalytic hydrodeoxygenation (HDO) of guaiacol using nickel-loaded cerium oxide (Ni/Ce) and molybdenum-promoted Ni/Ce (Mo-Ni/Ce) catalysts in supercritical ethanol. The use of Mo-Ni/Ce at 300 °C maximized H 2 production, guaiacol conversion (84.1%), and deoxygenation compared to Ni/Ce. Mo-Ni/Ce also achieved the highest efficiency for producing desired products, resulting in 7.8% phenol and 29.0% alkylphenols selectivities. Mo-Ni/Ce's better efficiency stemmed from enhanced ethanol dehydrogenation, H 2 dissociation and spillover, and accelerated HDO reactions owing to improved Ni dispersion and catalyst oxygen vacancies. Testing different Ni and Mo loading amounts revealed the optimum catalyst efficiency when using 20% Ni and 5% Mo (5Mo-20Ni/Ce). Temperature optimization with 5Mo-20Ni/Ce increased guaiacol conversion (up to 95.6% at 340 °C) and yielded more phenol (27.4%) and alkylphenols (66.1%). DFT calculations revealed that adding molybdena clusters notably reduced the energy required for creating oxygen vacancies, indicating enhanced catalytic properties for oxygen vacancy generation in 5Mo-20Ni/Ce. [Display omitted] • Catalytic guaiacol HDO was performed in supercritical ethanol without external H 2. • The use of Mo-Ni/Ce obtained the highest guaiacol conversion and deoxygenation. • A higher selectivity toward alkylphenols was achieved over Mo-Ni/Ce than Ni/Ce. • Catechol was proposed as the main intermediate produced by guaiacol demethylation. • The DFT calculations were employed to identify the optimal oxygen vacancy sites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalytic pyrolysis of sewage sludge for the production of aromatics is studied. • A higher yield of aromatics is obtained using HZSM-5 compared to HY and Hβ. • CH 4 decomposition environment outperforms CH 4 and N 2 for aromatics production. • The introduction of Ni or Mo on HZSM-5 increases the aromatics yield. • Co-impregnation of Ni and Mo on HZSM-5 further enhances the aromatics yield. Sewage sludge is solid waste resulting from wastewater treatment processes, and its improper management adversely affects the environment and human health. This study aims to convert sewage sludge into valuable aromatics, including benzene, toluene, ethylbenzene, and xylenes, or BTEX, via the catalytic pyrolysis using mono- and bimetal-modified protonated Zeolite Socony Mobil–5, or HZSM-5, catalysts under nitrogen, methane and methane decomposition conditions. In the methane medium, HZSM-5 yielded more BTEX (20.91 wt%) compared to those obtained using protonated Y zeolite (HY) (17.24 wt%) and protonated beta zeolite (Hβ) (11.70 wt%) owing to its proper acidity, higher shape selectivity, and higher methane activation. When HZSM-5 is used, the BTEX yield increased considerably in the methane decomposition environment (27 wt%), 1.29 and 1.46 times higher than those produced under methane and nitrogen, respectively. This increase is attributed to the dual effects of the surplus in situ hydrogen (H 2) and direct involvement of methane, which resulted in accelerated hydrocracking, hydrodeoxygenation, and co-aromatization reactions. Under methane decomposition conditions, the use of the Ni/HZSM-5, Mo/HZSM-5, and Ni-Mo/HZSM-5 catalysts led to 1.23-, 1.30-, and 1.66-fold increases in BTEX production, respectively, than that of the parent HZSM-5, owing to the dual effects of acidity enhanced by the newly formed Lewis acid sites, increased oxygen vacancies, and improved physical properties of the catalysts. Hence, the catalytic pyrolysis of sewage sludge using mono- and bimetal-modified HZSM-5 catalysts in a H 2 -rich environment proposed in this study is expected to be an efficient and sustainable method for converting undesirable materials into valuable biofuels. [ABSTRACT FROM AUTHOR]

As UV-light stabilizers, Bis(4-hydroxy)benzophenone (BBP), are extensively consumed to quench radicals from photooxidation, continuous release of BPs into the environment poses serious threats to the ecology in view of their xenohormone toxicities, and BBP shall be eliminated from water to avoid its adverse effect. Since sulfate radical (SR)-based chemical oxidation techniques have been proven as effective procedures for eliminating organic emerging contaminants, this study aims to develop useful SR-based procedures through activating Oxone for degrading BBP in water. In contrast to the conventional Co 3 O 4 , cobalt sulfide (CoS) is particularly proposed as an alternative heterogeneous catalyst for activating Oxone to degrade BBP because CoS exhibits more reactive redox characteristics. As structures of catalysts predominantly control their catalytic activities, in this study, a unique nanoplate-assembled CoS (NPCS) 3D cluster is fabricated via a convenient one-step process to serve as a promising heterogeneous catalyst for activating Oxone to degrade BBP. With NPCS = 100 mg/L and Oxone = 200 mg/L, 5 mg/L of BBP can be completely eliminated in 60 min. The catalytic activity of NPCS towards Oxone activation also significantly surpasses the reference material, Co 3 O 4 , to enhance degradation of BBP. E a of BBP degradation by NPCS-activated Oxone is also determined as a relatively low value of 42.7 kJ/mol. The activation mechanism as well as degradation pathway of BBP degradation by NPCS-activated Oxone was investigated and validated through experimental evidences and density functional theory (DFT) calculation to offer valuable insights into degradation behaviors for developing SR-based processes of BBP degradation using CoS catalysts. [Display omitted] • Nanoplate-assembled CoS (NPCS) is prepared via a one-step hydrothermal process. • NPCS activates Oxone to fully eliminate 5 mg/L of Bis(4-hydroxy)benzophenone (BBP). • NPCS outperforms the benchmark Co 3 O 4 NP for degrading BBP with E a = 42.7 kJ/mol. • NPCS can be reused up to 5 cycles to activate Oxone for degrading BBP completely. • DFT calculation is performed to elucidate degradation behaviors of BBP with Fukui index. [ABSTRACT FROM AUTHOR]

In order to evaluate the potential of C4 raffinate II as a feedstock for oligomerization reactions, the effects of 1,3-butadiene in C4 raffinate II on catalyst life were tested over Ni/Al2O3 catalysts in a fixed bed reactor. Catalytic deactivation by butadiene in the oligomerization of industrially produced C4 raffinate II could be mitigated by a reduction of 1,3-butadiene content, from 0.15 to 0.004 wt.%, through selective hydrogenation. To improve catalytic performance, phosphorous compounds were adapted as a promoter for the Ni/Al2O3 catalyst and octene selectivity was enhanced. The branching index of the product over the Ni–P–triphenyl phosphine oxide/Al2O3 catalyst is higher than that over other catalysts, which is desirable for the production of octenes as a raw material for gasoline blending. [Copyright &y& Elsevier]

• A new sustainable platform for plastic waste/CO 2 to syngas was investigated. • Catalytic pyrolysis promoted conversion of fishing net waste to syngas under CO 2 /N 2. • Coke formation resulted in Ni catalyst deactivation, but CO 2 suppressed it. • Continuous use of Ni catalyst under CO 2 was allowed for high production rate of H 2. A benign route for hydrogen (H 2) production is environmentally desirable. To achieve this, H 2 synthesis from polymeric waste was investigated. A new route was sought to maximize H 2 production with the least formation of coke during catalytic pyrolysis of fishing net waste (FNW) by using CO 2 (as reaction media) and a Ni/SiO 2 (as catalyst). The thermolytic characteristics of FNW were also evaluated under the CO 2 condition (and N 2 as reference environment) both with and without catalysts to assess the full scope of variabilities involved in catalytic pyrolysis of FNW. The use of Ni/SiO 2 catalyst in each of the N 2 and CO 2 conditions improved the reaction kinetics in terms of syngas formation with significant production of H 2 (1,543 and 770 mmol g−1 cat h−1) and CO (11 and 1157 mmol g−1 cat h−1), respectively. However, H 2 production rate dropped when the catalyst was deactivated due to (hydro)carbon deposition onto the catalyst surface under N 2 environment. Under CO 2 environment, CO 2 served as an oxidant during FNW thermolysis with additional CO formation and prolonged lifetime of catalyst (via suppressed deactivation). H 2 production mediated by CO 2 increased to ≥1,093 mmol g−1 cat h−1 during five repeated cycles of FNW pyrolysis, coupling with water–gas shift reaction (WGS: CO + H 2 O ⇌ H 2 + CO 2). This new approach to H 2 production is demonstrated as a practical measure for producing H 2 while extending catalyst life. [ABSTRACT FROM AUTHOR]

• Co-conversion of KL and LLDPE over mesostructured catalysts of ZSM-5 and Al-SBA-15. • A strong synergy between KL and LLDPE in aromatic hydrocarbons formation. • Hydrogen-donation of LLDPE pyrolyzates to lignin-derived vapors. • High catalytic activity of mesoZSM-5 caused by its higher acidity and MFI structure. Catalytic co-conversion of Kraft lignin (KL) and linear low-density polyethylene (LLDPE) over mesostructured catalysts was examined using a micro-pyrolyzer equipped with gas chromatography-mass spectrometry/flame ionization detector (MPy-GC/MS/FID). Mesoporous catalysts of Al-SBA-15 and mesoZSM-5 were synthesized and characterized by N 2 sorption, ammonia temperature programmed desorption, and X-ray diffraction. The characterization results indicated that mesoZSM-5 had the smaller average pore size (4.10 nm) than Al-SBA-15 (10.70 nm), but its total acidity (both weak and strong acid sites) was much higher than Al-SBA-15. When they were applied as catalysts in the pyrolysis of KL and LLDPE, the mesoZSM-5 exhibited higher catalytic activity for aromatic hydrocarbon production due to its higher acidity and MFI pore structure. Indeed, synergistic synthesis of aromatic hydrocarbons was achieved via the catalytic co-pyrolysis of KL and LLDPE because of the H-donating effect of LLDPE; the experimental yields (GC/MS area; abundance vs. time) of aromatic hydrocarbons in the oils obtained from catalytic co-pyrolysis of KL/LLDPE (1:1) over Al-SBA-15 (8.76 × 107) and mesoZSM-5 (27.58 × 107) were ∼1.5 fold higher than the theoretical yields. [ABSTRACT FROM AUTHOR]

A protonated form of Zeolite Socony Mobil-5 (H-ZSM-5) catalyst (with Si/Al = 200) was synthesized through a hydrothermal method from various sources of silica, including Ludox, silicic acid, and tetraethyl orthosilicate. We also investigated the effect of loading the catalyst with yttrium (Y), samarium (Sm), and gadolinium (Gd), respectively, on the acidic properties of the catalyst. We compared the catalytic performance of the catalysts with different loadings in methanol to hydrocarbon conversion. The catalysts were characterized using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, surface area analysis measurements, thermogravimetric analysis, and temperature-programmed desorption. Among the metal-loaded Ludox-based H-ZSM-5 catalysts (LHZs), the Sm/LHZ catalyst had the best performance with 68.8 % propylene selectivity due to its high amount of weak and intermediate acid sites at 480 °C, WHSV = 1 h−1 in a methanol to propylene conversion. However, the Gd-LHZ catalyst significantly increased the selectivity toward ethane and propane during the conversion. [Display omitted] • Sm loaded H-ZSM-5 showed the best performance for the MTP process. • Gd doping in H-ZSM-5 significantly increased paraffin selectivity. • Synergy between modified H-ZSM-5 and metal achieved enhanced propylene production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalytic air gasification of plastic waste-derived wax was carried out. • Ni/X-Al 2 O 3 (X = Ti, Sr, or La) catalysts were synthesized to produce H 2 -rich gas. • The use of 10Ni/5Ti-Al obtained the highest gas yield and H 2 selectivity. • Modification of Al 2 O 3 structure by Ti enhanced Ni dispersion and oxygen mobility. • Growing temperature up to 750 °C was conducive to enhancing H 2 selectivity. Catalytic air gasification of plastic waste-derived wax (PW) was performed using Ni/X-Al 2 O 3 (X = Ti, Sr, or La) catalysts to produce H 2 -rich gas for the first time. For this purpose, X-Al 2 O 3 supports were primarily synthesized by doping different promoters into the Al 2 O 3 structure, followed by the loading of Ni. The catalytic performances of prepared catalysts were compared with that of 10Ni/Al, prepared by impregnation of Ni into commercial γ-Al 2 O 3. Compared with using 10Ni/Al, the use of Ni/X-Al 2 O 3 catalysts resulted in higher activity and selectivity, wherein the highest gas yield (74.78 wt%) and H 2 selectivity (25.30 vol%) were achieved using 10Ni/5Ti-Al. Also, the coke yield effectively decreased when using Ni/X-Al 2 O 3 catalysts, particularly 10Ni/5Ti-Al, compared with using 10Ni/Al. These findings are ascribed to the versatile effects of well-dispersed metallic Ni active sites, increased density of Lewis acidic sites at the expense of Brønsted acid sites, and enhanced oxygen transfer capacity of the catalyst owing to Ti addition. Moreover, increasing the concentrations of Ni (up to 10 %) and Ti (up to 5 %) enhanced the catalytic activity and selectivity for H 2 production. Increasing the temperature (up to 750 °C) showed a positive effect on the production of H 2 -rich gas. Furthermore, varying the catalyst-to-feedstock ratio affected the gas yield and H 2 selectivity. [ABSTRACT FROM AUTHOR]

• Co-pyrolysis of cellulose and LLDPE over MgO catalysts was performed. • MgO catalysts with different surface area and acid/base properties were used. • MgO/C has largest surface area and adequate acid-base property. • MgO/C produced the largest amounts of aromatics. Various MgO impregnated catalysts were used for the catalytic co-pyrolysis (CCP) of cellulose and linear low-density polyethylene (LLDPE) at 600 °C in ambient pressure. Micro reactor-gas chromatography, a semi-batch reactor, was used as a reactor and gas chromatogram/mass spectrometry/flame ionization detector were used for product detection. Three kinds of MgO impregnated catalysts, MgO/Carbon (MgO/C), MgO/Al 2 O 3 , and MgO/ZrO 2 , were prepared by the impregnation of MgO to different supporting material s, C, Al 2 O 3 , and ZrO 2 , respectively. Activities of the three MgO-impregnated catalysts were compared with 1:5 of feedstock to catalyst ratio. MgO/C produced the highest quality oil, which consisted of a large amount of aromatic hydrocarbons during the catalytic pyrolysis (CP) of cellulose. When the MgO catalysts were applied to CCP, the selectivity to aromatic hydrocarbons over MgO/C were 13.42%, which were also much higher than those over the other catalysts, including bulk MgO, demonstrating the effectiveness of the MgO/C catalyst on aromatics formation. Importantly, the experimental BTEXs (benzene, toluene, ethylbenzene, xylenes) yields of CCP over MgO/C were also much higher than the theoretical yields, highlighting the effectiveness of hydrogen-rich LLDPE on the CP of cellulose over MgO/C. Further investigation of the cellulose/LLDPE mixing ratio showed that the amount of BTEXs during the CCP of cellulose and LLDPE could be maximized by adjusting the cellulose to LLDPE mixing ratio to 25:75. [ABSTRACT FROM AUTHOR]

A base catalyst is expected to suppress coke formation of the catalyst, leading to less catalyst deactivation and more efficient production of bio-oil. To examine the feasibility of a solid-base catalyst as a lignin pyrolysis catalyst, MgO loaded on supports with different textural, acid, and base properties (i.e. carbon, Al 2 O 3 , and ZrO 2) was applied. In addition, because the co-processing of biomass with plastic significantly improves the quality of bio-oil in the catalytic pyrolysis process, co-pyrolysis of lignin with linear low-density polyethylene was performed, and the effects of the MgO catalysts were analyzed. Thermogravimetric analysis and a tandem micro-reactor–gas chromatography/mass spectrometry system were used to evaluate the performance of the MgO catalysts in terms of thermal decomposition behavior and yield of monoaromatic hydrocarbons. Overall, MgO supported on carbon (MgO/C) showed the highest yield of aromatic hydrocarbons during the pyrolysis of lignin, due to its well-balanced acid/base sites and high surface area. Also, MgO/C exhibited the strongest positive synergy toward the production of aromatic hydrocarbons during co-pyrolysis, which suggests that a metal oxide with base properties supported on high-surface-area carbon could be an efficient catalyst for producing bio-oil with high energy density fuel additives from the lignin. • MgO supported on carbon, ZrO 2 and Al 2 O 3 are applied to the lignin pyrolysis. • MgO supported on carbon (MgO/C) exhibited the highest activity for aromatic production. • The high activity of MgO/C is due to its high surface area and well-balanced acid/base sites. • MgO/C exhibits the synergistic production of aromatics during the catalytic co-pyrolysis. • Effective deoxygenation of phenols to aromatics is possible over MgO catalyst. [ABSTRACT FROM AUTHOR]

Highlights • In-situ and ex-situ catalytic pyrolysis (CP) of EFB using mesostructured catalysts. • Higher efficiency of ex-situ CP in production of aromatic hydrocarbons over mesoMFI. • In-situ and ex-situ catalytic co-pyrolysis (CCP) of EFB and polypropylene (PP). • Enhanced formation of aromatic hydrocarbons by in-situ CCP of EFB/PP using mesoMFI. • Reduction of char/coke formation in the in-situ CCP of EFB/PP using mesoMFI. Abstract Mesostructured aluminosilicates of Al-MSU-F (commercial), Al-SBA-15 (home-made), and mesoMFI (a mesoporous aluminosilicate with MFI structure, home-made), with a silica-to-alumina ratio of 40, were used as catalyst for the in-situ catalytic pyrolysis (CP) of empty fruit bunches (EFB) at 600 °C. The highest selectivity to aromatic hydrocarbons in bio-oil was obtained over mesoMFI due to its higher acidity than Al-SBA-15 and Al-MSU-F. In addition, ex-situ CP of EFB using mesoMFI was compared with in-situ CP; the ex-situ configuration produced higher aromatic hydrocarbons than the in-situ configuration. Meanwhile, in-situ and ex-situ catalytic co-pyrolysis (CCP) of EFB (with a H/C eff ratio less than 0.3) and polypropylene (PP) (with a high H/C eff ratio about 2) were carried out using the mesoMFI at 600 °C to investigate the supplementary effect of PP on the deoxygenation of EFB-derived pyrolyzates for producing aromatic hydrocarbons. Ex-situ CCP of EFB/PP (with the mass ratios of 75/25, 50/50, and 25/75) resulted in a lower formation of aromatic hydrocarbons than the in-situ CCP. In addition, the thermal decomposition behavior of EFB, PP, and EFB/PP in non-catalytic and catalytic (mesoMFI) pyrolysis/co-pyrolysis was investigated using thermogravimetric analysis (TGA); use of catalyst reduced the temperature of PP thermal degradation, but did not change the maximum reactivity temperature of EFB degradation. [ABSTRACT FROM AUTHOR]

The catalytic oxidation of toluene with ozone at room temperature was carried out over hierarchically ordered mesoporous catalysts (CeO 2 (meso), Mn 2 O 3 (meso), ZrO 2 (meso), and γ-Al 2 O 3 (meso)) and Al 2 O 3 with various textural properties and phases (γ-Al 2 O 3 (meso), γ-Al 2 O 3 (13 nm), and α-Al 2 O 3) to examine the effects of the nature of the catalyst on the catalytic activity. The catalysts were characterized by N 2 -physisorption measurements, powder X-ray diffraction, temperature programmed reduction, X-ray photoelectron spectroscopy and scanning transmission electron microscopy with energy dispersive spectroscopy. Among the ordered mesoporous catalysts, γ-Al 2 O 3 (meso) had the highest toluene removal efficiency because of its highest surface area and pore volume, which in turn was selected for further investigation. Manganese (Mn) was introduced to various Al 2 O 3 to improve the toluene removal efficiency. Comparing the Mn-loaded catalysts supported on various Al 2 O 3 with different crystalline phases or pore structures, Mn/γ-Al 2 O 3 (meso), had the highest catalytic activity as well as the highest CO 2 /CO ratio. The higher activity was attributed to the larger surface area, weaker interaction between Mn and Al 2 O 3 , and larger portion of Mn 2 O 3 phase. The increase in ozone concentration led to an improvement in the carbon balance but this enhancement was insufficient due to the deposition of by-products on the catalyst. After long term tests at room temperature, the reaction intermediates and carbonaceous deposits of the used catalysts were identified. • Ordered mesoporous materials, γ-Al 2 O 3 , CeO 2 , Mn 2 O 3 , ZrO 2 , were used. • Effect of the crystalline phase and pore structure of Mn/Al 2 O 3 was investigated. • The catalytic activity of toluene O 3 oxidation over Mn/γ-Al 2 O 3 (meso) was highest. • The reaction intermediates and carbon deposits on the used catalysts were identified. [ABSTRACT FROM AUTHOR]

Abstract Acetaldehyde removal tests were performed to compare the catalytic activity of the Kraft lignin char (KC), KOH-treated Kraft lignin char (KKC), and activated carbon (AC) along with their impregnation with Mn in a plasma reactor. The gasification characteristics (syngas content, and H 2 /CO ratio) of yellow poplar were investigated using nickel catalysts supported on KC, KKC, AC, and γ-Al 2 O 3 in a U-type quartz reactor. KKC and Mn/KKC improved significantly the surface area and contents of O and N functional groups over the raw char. In particular, Mn/KKC showed the highest acetaldehyde-removal efficiency. The catalytic activity of Ni-impregnated KC, KKC, AC, and γ-Al 2 O 3 decreased in the order of Ni/KKC > Ni/AC > Ni/KC > Ni/γ-Al 2 O 3 for the gas yield and Ni/γ-Al 2 O 3 >Ni/KC > Ni/AC >Ni/KKC for the oil yield, respectively. The Ni/KKC provides a more conducive environment for gasification, resulting in larger amounts of syngas (H 2 and CO) in the product gases. Moreover, Ni impregnated with char may be the most inexpensive and effective solution for achieving maximum tar reduction and syngas generation. Highlights • Krfat lignin char and KOH treated Kraft lignin char were used as support of catalyst. • Metal was loaded on Kraft lignin char and KOH treated Kraft lignin char. • Mn/KKC showed higher removal activity of acetaldehyde via plasma-catalyst process. • Ni/KKC showed higher syngas production from gasification of yellow poplar. [ABSTRACT FROM AUTHOR]

[Display omitted] • The single atom catalysts (SACs) and dual atom catalysts (DACs) are discussed. • Substrate-specific dual-atomic sites for catalysis are discussed. • The photocatalytic solar fuel production using DACs are summarized and highlighted. • Future outlook analysis of DACs for photocatalytic energy applications. Dispersing active metals into theoretical atomic level has emerged as a cost-effective means for constructing catalysts, which are considered single-atom catalysts (SACs). SACs are integrated with various photocatalysts to serve as efficient platforms for solar energy conversion. Though SACs exhibit superior catalytic activity and selectivity owing to their maximum atomic utilization and high versatility of surrounding atomic configurations, the nature of SACs containing only one type of active site limits various chain reactions, inhibiting catalytic performance. To overcome these limitations, dual atom catalysts (DACs) have emerged as a new inventive material for boosting photocatalytic reactions. Thus, this review discusses the limitations of SACs and relative advantages of DACs, synthesis of dual atom sites on various substrates, identification of dual atomic sites through characterizations, and applications of DACs in various photocatalytic energy harvesting such as H 2 production, CO 2 reduction, and N 2 reduction. Finally, perspectives and future directions for increasing the photocatalytic performance of DACs-integrated photocatalysts are proposed. [ABSTRACT FROM AUTHOR]