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The present work is an attempt to optimize the proportion of H-ZSM-5 and Al-MCM-41 in the catalyst mixtures for lignocellulose biomass catalytic pyrolysis. The H-ZSM-5 proportions of 50.0, 66.7, 75.0, and 87.5 wt.% were examined for the upgrading of biomass pyrolysis vapors in the fixed bed reactor. The catalyst mixture of 87.5 wt.% H-ZSM-5 and 12.5 wt.% Al-MCM-41 was found most effective in this study, giving a 65.75% deoxygenation degree. An organic-rich bio-oil was obtained with 74.90 wt.% of carbon content, 8 wt.% of hydrogen content, 15 wt.% oxygen content, a 0.39 wt.% water content, and a high heating value of 34.15 MJ/kg. The highest amount of desirable compounds among the studied catalytic experiments, which include hydrocarbons, phenols, furans, and alcohols, was obtained with a value of 95.89%. A significant improvement in the quality of bio-oil with the utilization of H-ZSM-5 and Al-MCM-41 catalyst mixtures was the rise of desirable compounds in bio-oil. [ABSTRACT FROM AUTHOR]

Mechanism of the low cost catalysts used in this work. • Activated carbon is the only catalyst promoting the production of hydrocarbons. • Intermediates are easy to polymerize to char or coke without restriction of pores. • Moderate pore size determines the catalytic performance of the activated carbon. Catalytic fast pyrolysis of lignin was performed using low-cost materials with different acidities and textural properties as catalysts in the present work. The main focus is to understand the role of low-cost catalysts in the fast pyrolysis of lignin. The four most commonly used low-cost catalysts, ilmenite (FeTiO 3), bentonite (Al-Si-OH), activated carbon (AC) and red mud (RM), were selected. The results show that bentonite, red mud and activated carbon effectively enhance the dehydration reaction, which is regarded as the dominant way to eliminate oxygen during the pyrolysis process, due to the existence of strong acidic sites. However, only activated carbon is found to be effective in promoting the production of monocyclic aromatic hydrocarbons (MAHs). Two metallic catalysts, i.e., bentonite and red mud, have strong acidities but quite low surface areas and less porous structures. Therefore, the dehydrated intermediates produced are especially easy to repolymerize to form char or coke without the restriction of obtaining a porous structure during the pyrolysis process. Activated carbon has not only a certain acidity but also a rich porous structure. Lignin fast pyrolysis-derived oxygenates can diffuse and react on the well-dispersed active sites within the pores of activated carbons. The catalytic performance of the activated carbon are supposed to be determined by the pore size. Only pores of similar size to lignin fast pyrolysis-derived oxygenates (0.6–1 nm) seems to be effective for the production of MAHs. Pores larger or smaller than lignin fast pyrolysis-derived oxygenates both tend to cause coke deposition rather than MAHs formation. [ABSTRACT FROM AUTHOR]

A diagram is presented which illustrates thiourea-phosphine-catalyzed Morita-Baylis-Hillman reaction.

[Display omitted] • It is a novel study on catalytic pyrolysis of excavated waste. • Six Fe- and Ni- catalysts and three catalyst bed temperatures were considered. • Catalysts were prepared using sol–gel and impregnation methods. • The sol–gel catalysts outperformed the impregnation catalysts. • The FeNi sol–gel catalyst yielded 9 mmol H 2 and 76 mg CNTs per g sample_daf. Undeniably, non-sanitary landfills existing worldwide pose considerable environmental risks related to air, water and soil pollution. Despite that, the landfill mining concept does not spread swiftly around the world. To prevent its fading into oblivion, it is necessary to transform the perception of landfills as waste to seeing them as stocks of valuable materials. Guided by this idea, this novel study investigates the possibility of producing carbon nanotubes (CNTs) and hydrogen-rich gas, materials crucial for our transition towards a more sustainable future, from excavated waste as these. To the best of our knowledge, this is the first study on catalytic pyrolysis of excavated waste. For this purpose, excavated waste was subjected to pyrolysis followed by in-line catalytic decomposition of the produced pyrovapours. The impact of the catalyst type and catalyst bed temperature on the process performance was analysed. Six types of monometallic and bimetallic Ni- and Fe- based catalysts, synthesised using two methods (the sol–gel and the impregnation method), were considered. Three catalyst bed temperatures were taken into account, namely 700 °C, 800 °C, and 900 °C. The results showed that the bimetallic catalyst prepared by using the sol–gel method (FeNi/Al_Sg) outperformed the other analysed catalysts, yielding 9 mmol/g sample_daf of H 2 and 76 mg/g sample_daf of CNTs at 800 °C. The product yields and quality were comparable to those reported in the open literature for homogeneous plastic waste pyrolysis. Eventually, the future research directions were discussed. [ABSTRACT FROM AUTHOR]

Five aluminosilicate catalysts with different textural and acidic properties are used to study the influence of their acidic and porous properties on the coke formation during the fast catalytic pyrolysis of lignin. The competition between coke formation and target product (hydrocarbons) formation in regard to different pore sizes and Si/Al ratios is classified via performing X-Ray Diffraction (XRD), nitrogen adsorption-desorption, pyrolysis–gas chromatography–mass spectrometry (Py-GCMS), kinetic calculations, and thermogravimetric (TG)/temperature programmed oxidation (TPO) measurements. The results indicated that a pore size consistent with the critical diameters of the pyrolysis products of lignin is a prerequisite for a catalyst to reach a high selectivity for the desired products with less coke formation. A relatively large pore size can cause severe coke formation; however, large pores are favorable for increasing the reaction rate by increasing the diffusion efficiency. A catalyst with sufficient acidity is also essential for high selectivity towards target products. [Display omitted] • The effect of acidity and pore size of catalysts on the coke formation is studied. • Five aluminosilicate catalysts are used for lignin catalytic pyrolysis. • HZSM5-30 shows the best anti-coking performance and highest HCs selectivity. • Suitable pore size is the prerequisite for a high catalytic performance. [ABSTRACT FROM AUTHOR]

Catalytic tar removal from producer gas is critical for the economic feasibility of Municipal Solid Waste (MSW) gasification in the waste-to-energy(WtE) approach. Nickel- and noble-metal catalysts have the highest tar cracking activities, but they increase costs, use scarce materials, and generate dangerous byproducts. To overcome these drawbacks, naturally occurring materials should be used for tar cracking. In this paper, two nanomaterials, synthesized from oyster and mussel waste shells respectively, are used to clean syngas from MSW in a secondary tar cracking unit. We observed that they reform class 1 tar (heavy tars that condense at high temperatures at very low concentrations) into class 3 tar (light hydrocarbons that are not important in condensation) and benzene. Although both catalysts' composition and textural properties were identical, crystallite size and especially specific surface area variation was enough to generate a change in product selectivity. A larger crystallite size and SSA shows a soot yield reduction of 95% with respect to the non-catalytic case, simultaneously increasing the H 2 /CO at 1000 °C. • Two CaO rich catalysts doped with Sr were synthesized from oyster and mussels waste shells. • Both catalysts improve syngas H2:CO ratio, reduce class 1 tar and soot yield at high temperatures. • Soot reduction is accompanied by a class 5 tar reduction and by an increase in class 3 tar. • The crystallite size and specific surface area of the two catalysts directly affect the tar cracking product selectivity. • The syngas quality obtained using the oyster derived catalyst makes it ideal to use in tandem with Ni and noble-metal catalysts. [ABSTRACT FROM AUTHOR]

The use of catalytic fast pyrolysis (CFP) of biomass to produce high-quality bio-oils as potential substitutes for conventional fuels plays an essential role in the decarbonization of the world. In this study, continuous CFP tests of sawdust using three commercial-ready catalysts were performed. The overall objective is to screen appropriate catalysts and catalyst loading amounts for further commercialization and upgrading by evaluating the quality of the organic fraction bio-oils and clarifying the relationship between the hydrogen-to-carbon atomic effective (H/C eff) ratio and bio-oil yield. The results displayed that, owing to a cracking effect of the catalyst, all catalytic cases had higher H/C eff ratios and larger relative area percentages of hydrocarbons determined by NMR. Thermogravimetric analysis reveals that, compared to non-catalytic bio-oils, catalytic bio-oils showed more distillates in the diesel range. Increasing the catalyst-loading amount also showed the same effect. Overall, all bio-oil products from catalytic cases had H/C eff ratios higher than 0.6, indicating the production of promising oil for hydrodeoxygenation. By analyzing and fitting the data from this work and comparing with the literature, it could be concluded that its yield would decrease as the bio-oil product quality increases (the H/C eff ratios increase). [Display omitted] • Continuous CFP tests were conducted, providing insight for scaling up. • Three different commercial-ready catalysts with two WHSV values were studied. • All catalysts-induced oil products with H/C eff higher than 0.6. • SA catalyst induced the most attractive oil production at WHSV of 0.5. • A negative correlation between H/C eff ratio and bio-oil yield was verified. [ABSTRACT FROM AUTHOR]

Carbon and H 2 recoveries from plastic waste enable high value-added utilizations of plastic waste while minimizing its GHG emissions. The objective of this study is to explore the use of a metal-free biocarbon catalyst for waste plastic pyrolysis and in-line catalytic cracking to produce H 2 -rich gases and carbon. The results show that the biocarbon catalyst exhibits a good catalytic effect and stability for various plastic wastes. Increasing the C/P ratio from 0 to 2, induce an increase in the conversion rate of C and H in plastics to carbon and H 2 from 57.1% to 68.7%, and from 22.7% to 53.5%, respectively. Furthermore, a carbon yield as high as 580.6 mg/g plastic and an H 2 yield as high as 68.6 mg/g plastic can be obtained. The hierarchical porous structure with tortuous channels of biocarbon extends the residence time of pyrolysis volatiles in the high-temperature catalytic region and thereby significantly promotes cracking reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] CaO shows a good capacity of CO2 adsorption at devolatilization stage of MSW. [•] CaO acted as a catalyst both in MSW devolatilization and char steam gasification. [•] Good dispersion and mobility of calcium in char were observed. [•] Catalytic mechanism during devolatilization and char gasification were discussed. [ABSTRACT FROM AUTHOR]

Abstract: A new carbon capture and recycle (CCR) system based on multi-reforming of CH4 with CO2 is proposed in this study. The aim was to develop a novel method to remediate greenhouse gases (CO2) using a high temperature (over 1173 K) process of reforming CH4 and/or O2, and/or H2O without catalysts. Using this novel method, the reactants are individually preheated to over 1173 K using a ceramic honeycomb heat exchanger, and then these high temperature streams enter the reactor to start the reforming reactions. Both thermodynamic and experimental studies were carried out on this novel method. Thermodynamic equilibrium models were built for four types of reforming, including dry reforming, bi-reforming, auto-thermal reforming, and tri-reforming. Only dry reforming was experimentally tested. The feasibility of this novel technology was proven by simulated and experimental results. High temperatures significantly promoted the multi-reforming process while avoiding the problem of catalyst deactivation. The experimental results on the direct system also showed that potential improvements in the efficiency of the novel technology could be achieved by optimizing the reforming reactants. Therefore, a continuous system was proposed. Moreover, the power source for the application of CCR systems was also discussed. [Copyright &y& Elsevier]