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An efficient approach for synthesis of levulinate from biomass‐derived levulinic acid (LA) and n‐butyl alcohol (BuOH) in molten salt hydrates (MSH) with microwave irridiation was reported. A series of molten salt hydrates were evaluated in terms of their catalytic activity and pH value without any additional catalyst. Introduction of AlCl3 greatly increased the yield of butyl levulinate(BL). As high as 95.5 % BL yield was obtained in LiCl ⋅ 3H2O+AlCl3 system. Reaction mechanism study shows that LiCl ⋅ 3H2O can promote the esterification of LA with BuOH by enhancing the protonation of LA. LiCl is able to expel the formed BL into organic‐phase, and then boost up esterification efficiency. Both separation of BL and strong hygroscopicity of LiCl ⋅ 3H2O promoted the esterification reaction equilibrium. High‐efficient esterification of LA with BuOH realized separation of LA from MSH. Activation energies of BL formation are 70.9 kJ/mol in LiCl ⋅ 3H2O and 31.8 kJ/mol in AlCl3+LiCl ⋅ 3H2O. [ABSTRACT FROM AUTHOR]

Hierarchical zeolites are promising for the development of biomass catalytic fast pyrolysis; composite molecular sieves with efficient catalytic activity are needed to expand their practical applications. Micro–mesoporous ZSM-5/SBA-15 composite molecular sieves doped with different amounts of Ga element were successfully synthesized via an isometric impregnation method. The physical structures of the prepared materials were characterized by energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and pyrolysis infrared spectroscopy. Based on these analyses, Ga was distributed uniformly on the surface of the composite molecular sieve catalyst. As Ga loading increased, Brønsted–Lewis (B + L) acids increased. Pyrolysis of rice hull was performed using a multi-function catalyst evaluation device and catalytic performance and anti-coking performance were evaluated. Ga-modified ZSM-5/SBA-15 showed better benzene, toluene, and xylene (BTX) catalytic selectivity and anti-coking properties compared to those of undoped catalysts. Additionally, the 2%Ga-ZSM-5/SBA-15 zeolite composite showed the best BTX catalytic selectivity, with a BTX yield of 25.52%, clearly demonstrating its potential for application in BTX production and practical uses in petrochemical industries. [ABSTRACT FROM AUTHOR]

Conversion of cellulose into glucose is one of the important approaches to biomass utilization, but the insolubility of cellulose in water makes it difficult to hydrolyze particularly in the case of heterogeneous catalysis due to the mass transfer obstacle between solid catalyst particles and cellulose particles. Temperature-responsive HCl-releasing catalysts have unique characteristic as they allow to catalyze the hydrolysis reaction of cellulose under homogeneous catalysts while the released HCl can be recovered and reused via simple cooling after reaction. In this paper, three mesoporous N-doped carbon materials (CNs) with temperature-responsive HCl-releasing ability were synthesized by carbonization of aminoguanidine hydrochloride at 400, 500 and 600 °C respectively. The basicity and the temperature-responsive HCl-releasing behavior of the as-prepared CNs are examined by means of acid–base titration and high temperature releasing experiment. The experimental results show that, of the three samples, CN-400 possesses the maximum HCl intake of 1.28 mmol HCl/g and can release about 1.15 mmol HCl/g when being heated to 220 °C. Employing CN-400·nHCl as the catalyst, a total reducing sugars (TRS) yield of 81.1% and 61.1% glucose yield can be obtained after reaction under 220 °C for 60 min. The considerable basic sites are derived from the pyridine nitrogen and indispensable for HCl-releasing to catalyze cellulose hydrolysis. Furthermore, CN-400·nHCl possesses excellent catalytic stability. Temperature-responsive acid-releasing catalysts provide a novel and green solid-liquid phase cellulose conversion reaction system. [ABSTRACT FROM AUTHOR]

Herein, spherical and nanosheet-like SAPO-11s were successfully synthesized hydrothermally and utilized to catalyze the methanol-to-gasoline (MTG) process. The nanosheet-like SAPO-11 (SAPO-11-A) had a thickness of about 10 nm, while the spherical SAPO-11 (SAPO-11-B) had a particle size of around 11 μm. Compared to SAPO-11-B, the property of SAPO-11-A was enhanced by 42.9% in specific surface area (SSA), 38.1% in mesopore volume (V me) and 20.2% in acid amounts, respectively. In terms of catalytic performance during the MTG reaction, SAPO-11-A demonstrated superior results not only in the methanol conversion (95.82%), gasoline-range hydrocarbons selectivity (58.76%) and iso/nparaffin ratio (8.17) but also in suppressed coke deposition (2.56%) compared with those (90.63%, 50.95%, 4.75 and 5.73%, respectively) of SAPO-11-B. Additionally, the optimal MTG process conditions were identified utilizing SAPO-11-A, demonstrating a methanol conversion rate of 98.34%, a gasoline hydrocarbon selectivity of 67.61%, an isoparaffin selectivity of 36.01% and an iso/nparaffin ratio of 10.94 at 380 °C, weight hourly space velocity (WHSV) of 2 h−1 and 1 MPa. These results highlight the potential of nanosheet SAPO-11 to produce gasoline-range hydrocarbons rich in isoparaffins. [Display omitted] • 2D nanosheet-like and spherical SAPO-11s were prepared via hydrothermal route. • 2D SAPO-11 gave a nanosheet-like morphology with a thickness of about 10 nm. • 2D SAPO-11 had better activity and stability than spherical SAPO-11. • Gasoline hydrocarbons rich in isoparaffins were obtained by 2D SAPO-11. [ABSTRACT FROM AUTHOR]

Improving the anti-coking performance of catalyst during lignin-catalyzed pyrolysis without affecting the selectivity of the monocyclic aromatic hydrocarbons (MAHs) is a challenge. In this paper, a low-cost composite catalyst (CSHZ) was prepared using calcined spent bleaching clay (CSBC) as a binder for HZSM-5 to resolve the issue. In order to evaluate the performance of the composite catalyst, an ex-situ fast catalytic co-pyrolysis experiment was performed in a fixed-bed reaction system with lignin and spent bleaching clay (SBC) as raw materials. The impacts of the temperature, CSBC-to-HZSM-5 ratios, raw material-to-catalyst ratios, and cycle-regeneration times on MAHs distribution, are then studied. The selectivity of CSHZ11 (CSBS-to-HZSM-5 ratio of 1:1) for MAHs in bio-oil reached 78.02 % at 550 ℃ and the raw material-to-catalyst ratio of 1:1, which exceeded those of HZSM-5 alone by 19.12 %. After 3 reaction-regeneration cycles, the catalytic activity of CSHZ11 for MAHs was 71.11 % of fresh catalyst. The characterization (TEM, Py-IR, TGA, etc.) of the catalysts (fresh and discarded) revealed that the addition of CSBC regulated the acidity and pore channels of HZSM-5 and inhibited the formation of catalyst graphite-like coke. This study demonstrates the feasibility of using binder modification to improve the anti-coking performance of HZSM-5. It also serves as a reference for the integrated utilization of SBC and lignin. [Display omitted] • The system can realize the full resource utilization of SBC. • The CSBC improved the selectivity for MAHs by regulating the acidity of HZSM-5. • CSBC was used as a binder for HZSM-5 to improve catalyst strength and lifetime. • CSBC captured coke precursors to improve the life of catalyst. [ABSTRACT FROM AUTHOR]

Arundo donax, acknowledged for its elevated energy content, substantial biomass yield and rapid growth, stands as an alluring candidate for biofuel production. In this investigation, a molecular sieve-based catalyst was utilized to scrutinize the catalytic fast pyrolysis (CFP) of Arundo donax, aiming for the production of naphtha-range compounds. The study also encompassed the evaluation of pyrolysis product yields within a fixed-bed reactor. The systematic exploration included an assessment of the impacts arising from catalyst type, temperature, weight hourly space velocity (WHSV), and N 2 flow rate. The results demonstrated that at 500 °C, WHSV of 1 h−1 and N 2 flow rate of 300 ml/min, SAPO-11 exhibited a selectivity of 64.55% to naphtha-range compounds and 64.55% to isomerous naphtha-range compounds. This was in stark contrast to the control group, which contained no catalyst (with a selectivity of 41.40% and 3.19%, respectively), SAPO-41 (with a selectivity of 11.02% and 9.55%, respectively) and HZSM-5 (with a selectivity of 59.89% and 53.51%, respectively). Additionally, SAPO-11 yielded the highest bio-oil compared to other catalysts (SAPO-11 of 28.52 wt% > none of 19.48 wt% > HZSM-5 of 18.90 wt% > SAPO-41 of 13.11 wt%). The conclusions drawn from these findings imply that the synthesized SAPO-11 catalyst exhibited superior catalytic activity and isomerization proficiency in contrast to other catalysts (SAPO-41 and HZSM-5). Remarkably, under the specified conditions of SAPO-11 catalyst, temperature = 500 °C, WHSV = 1 h−1 and N 2 flow rate = 200 ml/min, the CFP process yielded a remarkable maximum absolute yield of the naphtha-range compound at 25.82 wt%, with an isomerized naphtha-range compound absolute yield of 25.35 wt%. • SAPO-11 was used for Arundo donax CFP in a fixed-bed reactor. • The conversion of Arundo donax into high-value naphtha was achieved. • SAPO-11 exhibited excellent selectivity and isomerization towards naphtha. • Optimization of multiple process parameters was carried out. [ABSTRACT FROM AUTHOR]

Syngas is a key precursor for synthesizing gasoline (C 5 -C 11) hydrocarbons, offering an efficient route for utilizing non-petroleum carbon sources. However, the conventional Fischer-Tropsch synthesis (FTS) process faces a constraint with a maximum 45% selectivity for C 5 -C 11 , attributed to the Anderson-Schultz-Flory (ASF) distribution. Herein, bifunctional catalysts comprising ZnZrO x with different Zr/Zn ratios along with SAPO-11 zeolite sieves featuring varied morphologies like nanosheets (SA-A), petals (SA-B), and spheres (SA-C) have been effectively formulated and employed for the syngas-to-gasoline hydrocarbons (STG) reaction. Notably, the selectivity toward C 5 -C 11 far exceeded the ASF limits. Under identical reaction parameters, the Zn 1 Zr 4 O x /SA-A catalyst demonstrated notable enhancements of 6.6% and 26.2% in CO conversion, along with 4.6% and 7.6% increases in C 5 -C 11 selectivity, as compared to that of Zn 1 Zr 4 O x /SA-B and Zn 1 Zr 4 O x /SA-C catalysts, respectively. Furthermore, under the ideal conditions (380 °C, 4.5 MPa and gas hourly space velocity (GHSV) of 2400 mL min−1 g−1), Zn 1 Zr 4 O x /SA-A exhibited an exceptional C 5 -C 11 selectivity of 69.8% (CO 2 -free) alongside a single-pass CO conversion of 30.4%. Impressively, isoparaffin constituted 39.2% of the total composition, with the iso/n-paraffin ratio reaching 11.8. Even after 100 h, the catalyst maintained its remarkable catalytic activity, with the CO conversion and C 5 -C 11 selectivity maintaining levels of 27.5% and 66.85%, respectively. [Display omitted] • Zn 1 Zr 4 O x /SA-A bifunctional catalyst enables direct syngas to gasoline conversion. • Zn 1 Zr 4 O x /SA-A achieved 69.8% C 5 -C 11 selectivity, 30.4% single-pass CO conversion. • Notably, the selectivity toward C 5 -C 11 far exceeded the ASF limits. • Remarkably, isoparaffin was 39.2% of the total, iso/n-paraffin ratio reached 11.8. • Post 100 h, catalyst still retained 27.5% CO conversion, 66.8% C 5 -C 11 selectivity. [ABSTRACT FROM AUTHOR]

Direct syngas conversion for diesel fuel becomes an attractive route for its possibility of utilizing non-petroleum carbon resources. However, there is a limited selectivity of around 36% for diesel hydrocarbons (C 9 -C 22) via the conventional Fischer-Tropsch process due to the Anderson-Schulz-Flory (ASF) constraint. Herein, bifunctional catalysts composed of zirconium dioxide (ZrO 2) dispersed on multi-walled carbon nanotubes (CNT) (ZrO 2 /CNT) were successfully designed and applied for direct conversion of syngas into diesel with selectivity far beyond the ASF limitation. At 350 °C with the pressure of 3 MPa, H 2 /CO of 2 and gas hourly space velocity of 2400 mL·h−1·g cat −1, ZrO 2 /CNT gave an unexceptionable C 9 -C 22 selectivity of 50.74% at a single pass CO conversion of 43.86% compared with those (9.11% and 20.55%, respectively) of ZnO/CNT and those (14.07% and 25.76%, respectively) of ZnO-ZrO 2 /CNT. The iso/n-paraffin ratio in the C 9 -C 22 reached up to 16. Moreover, after 100 h of operation, the catalyst still showed remarkable catalytic activity with CO conversion remaining at 40.61%, diesel hydrocarbon selectivity, and methane selectivity at 42.27% and 7.67%, respectively, while the by-product CO 2 selectivity was also stable at about 3.77%. [Display omitted] • Conversion of syngas to value-added diesel using ZrO 2 /CNT catalysts is feasible. • An improved CO conversion and excellent selectivity to diesel were obtained. • ZrO 2 /CNT catalyst showed 50.74% diesel selectivity and 43.86% CO conversion. • The mild reaction conditions make it feasible to produce diesel on a large scale. [ABSTRACT FROM AUTHOR]

Biomass-based carbon materials have been considered as promising catalysts for oxygen reduction reaction due to their abundant heteroatom, renewability, and low cost. However, their practical electrocatalytic applications face a series of challenges, including insufficient pore structure, active site density, and their uneven distribution. Herein, we report an ingenious strategy to fabricate the biomass-derived carbon materials with hierarchical structures and high nitrogen doping. More specifically, microbial fermentation was used to achieve efficient and homogeneous nitrogen introduction by degrading the compact structure of lignocellulosic biomass. In addition, the precise regulation of the pore structure for carbon material was achieved by further introduction of appropriate oxygen during the pyrolysis process. The carbon catalyst prepared by the cascading treatment exhibited better performance. Notably, the C 5 exhibited the highest surface area (858.17 m2g−1) and abundant nitrogen-containing active sites, and high graphitization degree, thus, the C 5 demonstrates an outstanding oxygen reduction reaction catalytic performance in a wide pH range (e.g., E onset : 0.85 V vs. RHE in neutral pH) and microbial fuel cells performance (maximum power density of 741.6 mWm−2). This study provides new ideas for the activity regulation of carbon electrocatalysts derived from biomass and will open the door to its large-scale application. • Cascading pre-treatment was effective to fabricate the carbon catalysts. • Biological treatment was beneficial for the introduction of nitrogen atoms. • The oxygen etching can adjust the carbon structure and local graphitization degree. • 5% (vol%) oxygen content showed the best performance for oxygen reduction reaction. • The optimized catalyst showed good performance in a universal pH range. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) morphology zeolites nanosheets NS-M-SAPO-34 (M = K and Sr) were developed and applied for producing ethylene (C 2 H 4) from bioethanol. Various factors, including SAPO-34 type, temperature, bioethanol concentration, and weight hourly space velocity (WHSV) on C 2 H 4 production were evaluated. The synthesized NS-M-SAPO-34s gave a nanosheet-like morphology with a thickness of 25–50 nm, while the commercial cube-like SAPO-34 (CC-SP34) exhibited a cubic-like morphology with a particle size of about 1.5 μm. The specific surface area of the NS-Sr-SAPO-34 was 644 m2 g−1 which was much larger than that of CC-SP34 (573 m2 g−1). The catalytic performance evaluated by bioethanol dehydration reaction showed that NS-Sr-SAPO-34 exhibited significant improvements not only in suppressed coke deposition (5.6%) and prolonged lifetime (913 min) but also in higher C 2 H 4 yield (94.5%) compared with those (11.8%, 160 min and 82.4%, respectively) of CC-SP34, which can be attributed to the shortened diffusion path length, highly accessible active centers and suitable medium-strong acidity. Elevated temperature, high bioethanol concentration and decreased WHSV tended to enhance the C 2 H 4 yield, while decreased bioethanol concentration was propitious to suppress coking rate. An optimal C 2 H 4 yield of 100% was obtained at 350 °C with a bioethanol concentration from nutrient broths (15 vol%, WHSV = 0.75 h−1). [Display omitted] • 2D M-SAPO-34s (M = K and Sr) were prepared via hydrothermal + ion-exchange route. • 2D M-SAPO-34s gave a nanosheet-like morphology with a thickness of 25–50 nm. • 2D M-SAPO-34 had better activity and stability than cube-like SAPO-34. • 2D Sr-SAPO-34 gave the highest activity and good resistance to coke deposition. [ABSTRACT FROM AUTHOR]

The use of low-cost and high-efficiency catalysts is a promising approach to remove tar and increase the gas yield in the catalytic reforming of biomass pyrolysis volatiles. In this study, using rice husk biochar (RHC) as a precursor, four typical activated biochar catalysts were prepared using both chemical (H 3 PO 4 and KOH) and physical (CO 2 and H 2 O) activators. The experiments demonstrated that high surface areas were obtained upon activation. The chemical activators introduced inorganic elements in the biochar, while physical activators were beneficial to the formation of high micropore volume. The effects of varying the catalyst type, catalyst to feedstock ratio, and catalytic cracking temperature on the tar decomposition efficiency and gas yield were studied. The results showed that maximum tar decomposition efficiency (91.75%) and gas yield (704.85 mL/g) were achieved using the RHC-KOH catalyst at a catalytic cracking temperature of 800 °C and a catalyst to feedstock ratio of 2:1. The introduction of the catalysts changed the gas composition, and the yield of H 2 /CO increased significantly. The increase in catalytic cracking temperature promoted the secondary cracking reaction of tar and the biochar self-gasification reaction in addition to facilitating the cyclopolymerization of some tar components. [Display omitted] • Biochar catalysts are prepared by using KOH, H 3 PO 4 , CO 2 and H 2 O activators. • Physical activators are beneficial to the formation of micropore volume. • The tar decomposition efficiency is 91.75% at 800 °C with KOH/corn straw of 2. • The increase in cracking temperature facilitates tar cyclopolymerization. [ABSTRACT FROM AUTHOR]

In this study, PEG/MgO/ZSM-5@Fe 3 O 4 magnetic catalyst was synthesized using polyethylene glycol (PEG) as a mediator, and was applied to the microwave-assisted in-situ transesterification of Spirulina platensis with ethanol. The effect of different proportion of mediator on catalyst performance was investigated. The composition, structure, morphology, specific surface area, magnetization and basicity of the catalysts were all characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), vibrating sample magnetometer (VSM) and Hammett indicator. The catalytic performance evaluation results showed that the highest yield of biodiesel could reach 95.8% under the optimum reaction condition using 15PEG/MgO/Z@Fe 3 O 4 catalyst. In addition, the catalyst can be reused for six times without leaching of active components, which still had a high conversion of biodiesel. Finally, the physicochemical properties of the biodiesel were also tested, which were in accordance with GB and EN standards. [Display omitted] • PEG-mediated catalyst had excellent catalytic performance. • The catalyst was applied to biodiesel production from Spirulina platensis. • FAEE maximum yield of 95.8% had been obtained with microwave-assisted. • Microwave could enhance the reaction process and increase the reaction rate. • The results showed that transesterification was non-spontaneous and endothermic. [ABSTRACT FROM AUTHOR]

[Display omitted] • LiCl hydrate is excellent medium for converting glucose to levulinic acid. • Temperature has prominent impact on the reactivity and selectivity. • Humins is predominantly derived from glucose due to the lack of Lewis acid. • A kinetic model was developed to describe glucose conversion to levulinic acid. • Activation energy and pro-exponential factor for each reaction were calculated. Conversion of glucose to 5-hydromethyl furfural (HMF) and levulinic acid (LA) was systematically investigated in LiCl·3H 2 O without additional catalyst. Based on the experimental investigations by using glucose, fructose and HMF as the reaction substrate separately, corresponding reaction kinetics in LiCl·3H 2 O were modelled by first-order assumption. Kinetic analysis demonstrates that high temperature favors the formation of LA, while low temperature facilitates to selectively form humins. To achieve high LA yield, at least a temperature of 140 °C is required. Without additional catalyst converting glucose to LA in LiCl·3H 2 O, humins was predominantly derived from glucose and HMF, and glucose isomerization is the reaction rate-determining step. The activation energies of the main reactions are 160.96 kJ/mol (glucose to HMF), 139.20 kJ/mol (fructose to HMF), and 71.81–76.48 kJ/mol (HMF to LA) respectively. The activation energies for humins formation were 23.45 kJ/mol from glucose, 49.54 kJ/mol from fructose, and 42.15–65.85 kJ/mol from HMF, respectively. It is verified that LiCl·3H 2 O, as compared to aqueous medium, is an excellent reaction medium for converting glucose to LA as it can provide the active centers for fructose to HMF reaction and HMF to LA reaction, but lack of highly efficient Lewis acid for glucose isomerization. With the addition of Lewis acid (such as AlCl 3 and FeCl 3), as high as 83.4% of LA yield can be obtained respectively when directly converting glucose, with the total selectivities of LA and HMF of 95%. [ABSTRACT FROM AUTHOR]

• Three novel carbon-based MgO solid bases were synthesized and characterized. • The catalytic activity of the MgO catalysts were evaluated for transesterification. • The MgO-UREA-800 exhibited remarkable activity for biodiesel synthesis. • FAEE yield maintained 85.7% after 5 transesterification runs. The main purpose of this work was to develop a highly efficient and stable solid base catalyst for the preparation of biodiesel to meet the needs for green and clean production. To this end, a series of carbon-based magnesium oxide (MgO) solid base catalysts with high specific surface area were prepared by a sol-gel method and calcination for biodiesel production from castor oil. The effects of different organic additives and calcination temperatures on the physicochemical properties of catalysts were analyzed and evaluated by XRD, SEM, EDX, BET, FTIR and TGA. SEM and BET results indicated that the carbon-based MgO catalysts have a proper particle size distribution and a higher specific surface area. Meanwhile, EDX and TG analysis evidenced the presence of residual carbon in the MgO samples, which was confirmed to have a positive effect on the performance of the catalysts. The transesterification reaction was carried out in a batch reactor with condensed reflux to assess the performance of the catalysts. The MgO-UREA-800 catalyst exhibited impressive catalytic performance and an optimum biodiesel yield of 96.5% was obtained at the molar ratio of ethanol to oil of 12:1, catalyst loading of 6 wt%, reaction temperature of 75 °C and reaction time of 60 min. The catalyst durability tests showed that the catalysts could be reused in five cycles of operation without significant losses in activity. [ABSTRACT FROM AUTHOR]