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Here, catalytic fast pyrolysis (CFP) was studied as a method to valorize rice husk (RH). Specifically, the effects of RH pretreatment, i.e., NaOH treatment, on the CFP efficiency and selectivity over a Ga-loaded HZSM-5 (SiO2/Al2O3 ratio = 38) were investigated. In addition to NaOH pretreatment, it was investigated how pyrolysis medium (N2, CH4, or a gas stream evolved from ex-situ CH4 decomposition over a Ni/La2O3/CeO2/Al2O3 catalyst (Ni/La2O3/CeO2 = 2/1/1) at 923 K (d-CH4)) influences the CFP of pretreated RH. The NaOH treatment reduced the content of ash and increased the content of cellulose in the RH sample. Thus, the effect of pyrolysis medium on the CFP of cellulose was studied at first, followed by that on CFP of NaOH-treated RH. With regard to the pyrolysis medium, the yield of aromatic compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) achieved with both cellulose and the NaOH-treated RH enhanced in an order; d-CH4 > CH4 > N2. The removal of ash from RH with the NaOH pretreatment increased the BTEX yield up to 22.3 wt% as ash (mineral impurities) affects pyrolytic behavior of cellulose and lowers accessibility of pyrolytic volatiles to acid sites on zeolite. This study gives helpful information about how different parameters influence the conversion of RH into BTEX via CFP process.

Household food waste (FW) was converted into biohydrogen-rich gas via steam gasification over Ni and bimetallic Ni (Cu-Ni and Co-Ni) catalysts supported on mesoporous SBA-15. The effect of catalyst method on steam gasification efficiency of each catalyst was investigated using incipient wetness impregnation, deposition precipitation, and ethylenediaminetetraacetic acid metal complex impregnation methods. H

Present study evaluated the catalytic steam gasification of furniture waste to enhance the biohydrogen production. To do this, 10 wt% nickel loaded catalysts on the variety of supports (Al2O3, CeO2, CeO2-La2O3, and CeO2–ZrO2) were prepared by the novel solvent deficient method. The hydrogen selectivity (vol%) order of the catalysts was achieved as Ni/CeO2–ZrO2>Ni/CeO2>Ni/Al2O3≃Ni/CeO2-La2O3. The best catalytic activity of Ni/CeO2–ZrO2 catalyst (~82 vol % H2 at 800 °C) was ascribed to the smaller size of nickel crystals, finely dispersed Ni on the catalyst surface, and Ce1-xZrxO2-δ solid solution. The role of Ce1-xZrxO2-δ solid solution in Ni/CeO2–ZrO2 catalyst was observed as bi-functional; acceleration of water-gas-shift and oxidation of carbon reaction. The high resistance of Ni/CeO2–ZrO2 towards the coke formation showed its potential to establish a cost-effective commercial-scale biomass steam gasification process. This study is expected to provide a promising solution for the disposal of furniture wastes for production of clean energy (biohydrogen).

Different types of cobalt-based mixed oxide catalysts (20 wt%Co/MgO, 5 wt%Cu-20 wt% Co/MgO, 20 wt%Co/50%MgO–50%Al2O3) were synthesized by the co-precipitation method and applied for hydrogen production from glycerol steam reforming. The catalysts were characterized using X-ray diffraction (XRD), H2-Temperature-programmed reduction (H2-TPR), CO2-Temperature Programmed desorption, CO-Chemisorption, and CHN techniques. The H2-TPR analysis showed the reducibility of cobalt-oxide (5Cu20CM; 5 wt%Cu-20 wt% Co/MgO) was enhanced by the copper, and reduction profiles of cobalt oxide shifted to a lower temperature (

Steam-gasification of linear low-density polyethylene (LLDPE) waste to hydrogen-rich gas has been studied systematically over nickel (10 wt.%) loaded on a variety of supports (Al2O3, CeO2, and CeO2-ZrO2) synthesized using a novel solvent deficient method (SDM). The hydrogen selectivity order of the catalysts was reported as Ni/CeO2-ZrO2>Ni/CeO2>Ni/Al2O3. The highest catalytic H2 selectivity of the Ni/CeO2-ZrO2 catalyst was reported to be ∼76 vol.%, and was attributed to the smaller nickel crystals that were finely dispersed on the support, and to formation of Ce1-xZrxO2-δ solid solutions. The Ce1-xZrxO2-δ solid solution in the Ni/CeO2-ZrO2 catalyst was observed to be bi-functional, thus reflecting the acceleration of the water gas shift and the oxidation of carbon to CO and CO2. The better resistance of the Ni/CeO2-ZrO2 catalyst towards coke deposition also indicated its potential for commercial-scale applications for the steam gasification of plastics. Therefore, this research provides an advanced route to recycle LLDPE plastic waste into hydrogen fuel, which presents both economical and environmental benefits.

In this study, conversion of n-propanal to produce 2-methyl-2-pentenal (C6 compound, a fuel range precursor) was carried out using AMW-SBA-15 catalyst synthesized from activated marble waste (AMW) consisting mainly of Ca2+ and Mg2+ ions. AMW-SBA-15 catalysts with different weight ratios of AMW/Si (6, 12, and 18 wt. %) were prepared using single step sol-gel method. The catalytic activities were examined using a fixed bed continuous reactor over temperature ranging from 350−425 °C under atmospheric pressure. The 12AMW-SBA-15 catalysts showed superior catalytic performance with n-propanal conversion of 75 % and C-6 compound selectivity of 81 % at 375 °C without the need of deactivation for 12 h. To elucidate the structure-activity relationship, all catalysts were characterized using a variety of techniques. The superior performance of 12AMW-SBA-15 was ascribed to the high surface area and smaller particle size as well as the high hydrophobicity, which controlled the hydration of Ca2+/Mg2+ ions during the reaction.

Ni-based catalysts (Ni, Ni–La2O3, and Ni–La2O3–CeO2) on mesoporous silica supports (SBA-15 and KIT-6) were prepared by an incipient wetness impregnation and tested in glycerol steam reforming (GSR) for hydrogen-rich gas production. The catalysts were characterized by the N2-physisorption, TPD, X-ray diffraction (XRD), SEM-EDS, and TEM techniques. N2-physisorption results of calcined catalysts highlight that adding of La2O3 increased surface area of the catalyst by preventing pore mouth plugging in SBA-15, which was frequently observed due to the growth of NiO crystals. A set of GSR experiments over the catalysts were performed in an up-flow continuous packed-bed reactor at 650 °C and atmospheric pressure. The highest hydrogen concentration of 62 mol% was observed with a 10%Ni–5%La2O3 –5%CeO2/SBA-15 catalyst at a LHSV of 5.8 h−1. Adding of CeO2 to the catalyst appeared to increase catalytic stability by facilitating the oxidative gasification of carbon formed on/near nickel active sites of Ni–La2O3–CeO2/SBA-15 and Ni–La2O3–CeO2/KIT-6 catalyst during the glycerol steam reforming reaction.

The importance of La2O3 or both La2O3 and CeO2 promoters on the formation of nickel phyllosilicate (Ni3Si4O12H2) as a precursor of Ni/SBA-15 for ethanol steam reforming (ESR) was investigated. The catalyst was made by a one-step modified conventional triblock copolymer synthesis method (pH-Adjustment with ammonium hydroxide). The prepared catalysts were characterized by N2 adsorption/desorption isotherms, XRD, H2-TPR, SEM-EDS and TGA-DSC techniques. The N2 adsorption/desorption isotherms identified the mesoporous nature of the catalysts and the XRD patterns of the calcined catalysts confirmed the formation of nickel-phyllosilicate structure. The H2-TPR analysis revealed that the La2O3 loading considerably increased the interaction between nickel and silica frame work of SBA-15 support. The ability of these catalysts for hydrogen production from ethanol steam reforming (ESR) was evaluated in a packed bed reactor at 650 °C. In the case of Ni/SBA-15 catalysts without and with La2O3 promoter, the ESR experiments experienced metal sintering and coke formation. Meanwhile, the catalytic activity of both La2O3 and CeO2 promoted Ni/SBA-15 catalyst (Ni-La2O3-CeO2/SBA-15) remained stable with time on stream in terms of GPR and hydrogen selectivity. The stable performance of this catalyst was explained by the strong interaction of nickel with SBA-15 promoted by La2O3 and the suppression of coke formation by CeO2.

Food waste, a renewable resource, was converted to H

Solid waste residues from the extraction of essential oils are projected to increase and need to be treated appropriately. Valorization of waste via pyrolysis can generate value-added products, such as chemicals and energy. The characterization of lemon myrtle residues (LMR) highlights their suitability for pyrolysis, with high volatile matter and low ash content. Thermogravimetric analysis/derivative thermogravimetric revealed the maximum pyrolytic degradation of LMR at 335 °C. The pyrolysis of LMR for bio-oil production was conducted in a fixed-bed reactor within a temperature range of 350–550 °C. Gas chromatography-mass spectrometry showed that the bio-oil contained abundant amounts of acetic acid, phenol, 3-methyl-1,2-cyclopentanedione, 1,2-benzenediol, guaiacol, 2-furanmethanol, and methyl dodecanoate. An increase in pyrolysis temperature led to a decrease in organic acid and ketones from 18.09% to 8.95% and 11.99% to 8.75%, respectively. In contrast, guaiacols and anhydrosugars increased from 24.23% to 30.05% and from 3.57% to 7.98%, respectively.

Food waste, a renewable resource, was converted to H2-rich gas via a catalytic steam gasification process. The effects of basic oxides (MgO, CaO, and SrO) with 10 wt% Ni/Al2O3 on the gasification properties of food waste were investigated using a U-shaped gasifier. All catalysts prepared by the precipitation method were analyzed by X-ray diffraction, H2-temperature-programmed reduction, NH3-temperature-programmed desorption, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The Ni/Al2O3 catalyst was reduced incompletely, and low nickel concentrations were detected on the surface of the alumina. The basic oxides minimized the number of acid sites and suppressed the formation of nickel-aluminate (NiAlxOy) phase in catalyst. In addition, the basic oxides shifted nickel-aluminate reduction reaction to lower temperatures. It resulted in enhancing nickel concentration on the catalyst surface and increasing gas yield and hydrogen selectivity. The low gas yield of the Ni/Al2O3 catalyst was attributed to the low nickel concentration on the surface. The maximum gas yield (66.0 wt%) and hydrogen selectivity (63.8 vol%) of the 10 wt% SrO- 10 wt% Ni/Al2O3 catalyst correlated with the highly dispersed nickel on the surface and low acidity. Furthermore, coke deposition during steam gasification varied with the surface acidity of the catalysts and less coke was formed on 10 wt% SrO- 10 wt% Ni/Al2O3 due to efficient tar cracking. This study showed that the steam gasification efficiency of the Ni/Al2O3 catalyst could be improved significantly by the addition of SrO.

Herein, the thermocatalytic conversion of rice husk is studied as a valorization method for the production of benzene, toluene, ethylbenzene, and xylene (BTEX). The reaction environment, the type of zeolite, the SiO2/Al2O3 ratio of the zeolite, and the Ga loading on the zeolite are considered in order to maximize the BTEX yield. Five distinct reaction media are tested, including N-2, CH4, and gas streams evolved from the ex-situ decomposition of CH4 at 650, 725, and 800 degrees C (designated as CH4-D(650), CH4-D(725), and CH4-D(800), respectively). The thermocatalytic conversion of rice husk in CH4-D(650) with a H-2/CH4 molar ratio of 0.88 is shown to provide the highest BTEX yield. In addition, the use of the HZSM-5 zeolite, with its relatively low SiO2/Al2O3 ratio, is shown to provide a further increase in the BTEX yield due to the higher density of Bronsted acid sites. The highest yield of BTEX (18.3 wt%) is achieved in the presence of Ga/HZSM-5 (Ga loading: 1 wt%) under the CH4-D(650) atmosphere. The further addition of Ga to the HZSM-5 (2 and 5 wt% Ga) is shown to decrease the BTEX yield because excess Ga loading on the zeolite decreases the number of available Bronsted acid sites. The present study provides useful information on the effects of various factors upon the thermocatalytic conversion of waste biomass such as rice husk to achieve high yields of value-added chemicals such as BTEX.

This work investigated the impact of pyrolysis medium and catalyst on the production of bio-BTX (benzene, toluene, and xylene) from Quercus Mongolica (Q. Mongolica) via catalytic pyrolysis. Two different pyrolysis media (N2 and CH4) and five different zeolite catalysts (HY, HBeta, HZSM-5, 1 wt% Ni/HZSM-5, and 1 wt% Ga/HZSM-5) were considered for the Q. Mongolica pyrolysis. The HZSM-5 yielded more BTX than the HY and HBeta due to its strong acidity. The employment of CH4 as the pyrolysis medium improved the BTX yield (e.g., 2.7 times higher total BTX yield in CH4 than in N2) and resulted in low coke yield (e.g., 5.27% for N2-pyrolysis and 2.57% for CH4-pyrolysis) because the CH4-drived hydrogen simulated a hydropyrolysis condition and facilitated dehydroaromatization reaction. CH4 also led to direct coupling, Diels-Alder, and co-aromatization reactions during the pyrolysis, contributing to enhancing the BTX yield. The addition of Ga to the HZSM-5 could further increase the BTX yield by means of facilitating hydrocracking/demethylation and methyl radical formation from CH4 assisting the generation of >C2 alkenes that could be further converted into BTX on acid sites of the HZSM-5.

This study investigated the potential of sawdust from the processing of Acacia wood for the furniture making industry to produce bio-oil and biochar in an auger pyrolysis reactor system. The necessary characterization to assess the suitability of feedstock and strategies the pyrolysis parameters was also carried out. The volatile matter, ash content, carbon content and the higher heating value of the sawdust feedstock were reported as 68.46 wt%, 1.13 wt%, 47.40 wt% and 19.33 MJ/kg, respectively, with very low nitrogen and sulfur content. The thermogravimetric (TGA and DTG) analysis of sawdust showed that the weight loss from biomass occurred in three main stages as a result of the removal of moisture and extractives, decomposition of hemicellulose, cellulose, and the lignin components. Based on the decomposition temperature window and peak conversion temperature the pyrolysis experiments were carried out in the range of 400–600 ℃ by maintaining the nitrogen flow rate, biomass feeding rate, rotation speed of the conveyer the residence time of materials and biomass particle size as 300 cm3/min, 180 g/h, 4.5 RPM, 5 min, and 0.5–1.0 mm, respectively. The yields of the non-condensable gases, biochar and bio-oil were reported in the ranges 16.70–38.47 wt%, 29.72–51.85 wt% and 29.40–45.10 wt%, respectively. The pyrolysis products were pragmatically analyzed to evaluate the influence on yield and their properties. The higher heating values of bio-oil produced were reported in the range 28.781–29.871 MJ/kg while the pH of bio-oil indicated the strongly acidic nature with values in the range of 2.9–3.4. Chemical compounds in bio-oils were categorized as phenols, nitrogen containing compounds, guaiacols, organic acids, ketones, anhydrous sugars, esters, and aldehydes. Biochar characterization showed an energy potential comparable to those of the low ranked coals with the higher heating values reported in the range of 25.01–25.99 MJ/kg. The surface morphological characteristics and Brunauer–Emmett–Teller (BET) analysis of the biochars indicated potential for other valued applications in the adsorption, environmental, catalyst, and agricultural context.

The present study examined the effects of the pyrolysis environment on BTEX (benzene, toluene, ethylbenzene, and xylenes) production in the catalytic upgrading of yellow poplar pyrolysis vapors. Three different gas environments, N2, CH4, and pre-decomposed CH4 stream (10 wt%-Ni/5 wt%-La2O3-5 wt% CeO2-Al2O3), which is a mixture of H2 (55.62%) and CH4, were studied using two types of zeolite catalysts, HZSM-5, and 1 wt% Ga/HZSM-5. The BTEX yields were enhanced linearly in the order N2