Chemistry of Furan Conversion into Aromatics and Olefins over HZSM-5: A Model Biomass Conversion Reaction

Selective production of methylindan and tetralin with xylose or hemicellulose

Indan and tetralin are widely used as fuel additives and the intermediates in the manufacture of thermal-stable jet fuel, many chemicals, medicines, and shockproof agents for rubber industry. Herein, we disclose a two-step route to selectively produce 5-methyl-2,3-dihydro-1H-indene (abbreviated as methylindan) and tetralin with xylose or the hemicelluloses from agricultural or forestry waste. Firstly, cyclopentanone (CPO) was selectively formed with ~60% carbon yield by the direct hydrogenolysis of xylose or hemicelluloses on a non-noble bimetallic Cu-La/SBA-15 catalyst. Subsequently, methylindan and tetralin were selectively produced with CPO via a cascade self-aldol condensation/rearrangement/aromatization reaction catalyzed by a commercial H-ZSM-5 zeolite. When we used cyclohexanone (another lignocellulosic cycloketone) in the second step, the main product switched to dimethyltetralin. This work gives insights into the selective production of bicyclic aromatics with lignocellulose.

Accelerated Synthesis of Nanolayered MWW Zeolite by Interzeolite Transformation

Hierarchical zeolites can offer substantial benefits over bulk zeolites in catalysis. A drawback towards practical implementation is their lengthy synthesis, often requiring complex organic templates. This work describes an accelerated synthesis of nanolayered MWW zeolite based on the combination of interzeolite transformation (IZT) with a dual-templating strategy. FAU zeolite, hexamethyleneimine (HMI), and cetyltrimethylammonium bromide (CTAB) were respectively employed as Al source and primary zeolite, structure directing agent, and exfoliating agent. This approach allowed to reduce the synthesis of nanolayered MWW to 48 h, which is a considerable advance over the state of the art. Tracking structural, textural, morphological, and chemical properties during crystallization showed that 4-membered-ring (4MR) units derived from the FAU precursor are involved in the faster formation of MWW in comparison to a synthesis procedure from amorphous precursor. CTAB restricts the growth of the zeolite in the c-direction, resulting in nanolayered MWW. Moreover, we show that this approach can speed up the synthesis of nanolayered FER. The merits of nanolayered MWW zeolites are demonstrated in terms of improved catalytic performance in the Diels-Alder cycloaddition of 2,5-dimethylfuran and ethylene to p-xylene compared to bulk reference MWW sample.

A density functional theory study on how γ-Al2O3 - Boehmite transformation affects carbon evolution during aqueous-phase reaction

Gamma-alumina (γ-Al2O3), one of the most common materials, is commercially used in many catalytic applications, including the active catalyst and support. However, the problem of fast deactivation makes the utilization of the γ-Al2O3 challenging. This work elucidates the mechanism of coke formation consisting of coke deposition and evolution on γ-Al2O3(110) surfaces in differential conditions, including; clean and hydroxylation γ-Al2O3(110) in terms of partial and fully hydroxylation of OH/γ-Al2O3(110) and AlOOH(010), respectively. We demonstrated that the γ-Al2O3(110) surface is proper for atomic coke deposition and dimerization in the initial state, where the presence of OH species promotes the coke evolution to higher coke, Cn (where n ≥ 3). Also, the higher coke formation thermodynamically preferred the cyclic form to the aliphatic one. The electron transfer from substrates to adsorbed coke illustrates the role of the electron donor of catalyst surfaces corresponding to the electron acceptor of adsorbed cokes.

Effects of steam and CO2 on gasification tar composition and evolution of aromatic compounds

The removal of tar is conducive to improving the energy efficiency of downstream equipment and reducing the damage caused to it. In this study, a two-stage continuous feeding apparatus was developed to explore the yield and characteristics of tar produced from the co-gasification of microcrystalline cellulose (MCC) and polyethylene (PE) under separate and mixed atmospheres of steam and CO₂. The tar yield can effectively reduce to 2.27 % when the steam and feedstock mass ratio (S/F) is 0.8. CO₂ can partially substitute the steam in the gasification process, which can effectively promote a decrease in benzofuran. Furthermore, Gaussian software was employed to analyze the evolution mechanism of aromatic compounds. When the temperature is more than 800 °C, hydrogen consumption in the benzene cracking process is reduced, which is instrumental in improving the quality of syngas. Naphthalene is prone to form through the recombination of two cyclopentadienyls. Controlling the cyclization of cyclopentadienyls is a critical step in reducing the formation of polycyclic aromatic hydrocarbons. H and OH radicals are critical in phenol and benzofuran cracking, respectively. Although radicals act differently on specific aromatic compounds, the gasification effect of CO₂ is less than that of steam because steam can provide both H and OH radicals, whereas CO₂ needs to consume H radicals to generate OH radicals. The results provide beneficial guidance for controlling tar formation.

Synthesis of Micromesoporous Zeolite-Alumina Catalysts for Olefin Production from Heavy Crude Oil

Maximizing the production of high-value olefins from heavy crude oil is a crucial topic in the downstream refining industry. However, converting heavier fractions is a major challenge due to the small pore size of the zeolites. Therefore, this work aimed to develop extrudate zeolite catalysts posing adequate micromesoporous pore network and moderate acidity by combining microporous zeolite with the boehmite phase of alumina. These extruded zeolite-alumina catalysts are expected to allow sufficient diffusion of heavy fractions, thus leading to high cracking of heavy oil into valuable olefins. Different zeolite-alumina catalysts of varying alumina content ranging from 25 to 75% (AlZ-25, AlZ-50, and AlZ-75) were prepared in the laboratory to study the optimum zeolite-alumina ratios for maximum olefin production from heavy oil. The catalysts were characterized for their chemical and physical properties using nitrogen adsorption (N2 adsorption), X-ray diffraction (XRD), inductively coupled plasma (ICP) spectrometry, Fourier transform infrared (FT-IR) spectroscopy, and NH3 temperature programmed desorption (TPD). A gradual increase in the average pore diameter (APD) of the catalysts was observed due to the alumina ratio with a distinct range of acidity that is in the range of 125 to 375°C, and also the geometry of pores is not the same for all of the supports. Catalytic performance tests were conducted in a fixed-bed reactor at 450°C, 10 bar, and liquid hourly space velocity (LHSV) of 1 h−1. The results revealed that the prepared catalysts were thermally stable and effective in heavy oil conversion to olefins. Moreover, the selectivity of propylene was higher than that of ethylene (P/E) due to the modified textural and acidic properties of the catalysts. The results showed that the catalysts prepared with moderate acidity and adequate mesopores exhibited a considerable effect on the conversion of heavy crude oil into olefins. Hence, the acidity and mesoporosity of the catalysts play a vital role in determining the catalyst performance.

Isomorphous Substitution of Gallium into MFI-Framework Zeolite Increases 2,5-Dimethylfuran to Aromatics Selectivity and Suppresses Catalyst Deactivation

The valorization of biomass-derived molecules into commodity chemicals is important for the transition to renewable feedstocks. The model platform molecule 2,5-dimethylfuran (2,5-dmf) can be converted into value-added aromatics such as benzene, toluene, and xylenes (BTX) over zeolite catalysts. To explore the role of the zeolite acid site(s) in BTX selectivity, gallium has been isomorphously substituted into the framework, resulting in a Ga-silicate. Compared to the ZSM-5 counterpart, this modification shows enhanced benzene selectivity as well as resistance to deactivation by coke in continuous catalytic performance tests.

Anchoring Effect of Organosilanes on Hierarchical ZSM-5 Zeolite for Catalytic Fast Pyrolysis of Cellulose to Aromatics

As an essential chemical feedstock, aromatics can be obtained from biomass by catalytic fast pyrolysis (CFP) technology, in which diffusion limitation is still a problem. In this study, several ZSM-5 zeolites with intercrystal stacking macropores were synthesized by adding organosilanes (OSAs) with different alkyl chain groups. Due to the structure-directing effect of the OSA, the prepared ZSM-5 zeolites possess a larger external surface area and pore volume than Blank-Z5. Moreover, the pore size is related to the extent of anchoring of the OSA and silicon-aluminum species in the zeolite precursor. Pyridine Fourier transform infrared (Py-FTIR) and NH₃-temperature-programmed desorption (TPD) analyses show that the obtained ZSM-5 zeolites have a higher Brønsted acidity and total number of acid sites. In addition, excessive addition of OSA is not conducive to the growth of ZSM-5 zeolites. The catalytic performance of the synthesized ZSM-5 zeolites was evaluated by Py-GC/MS. The larger external surface area and pore volume improve the accessibility of the acid sites and thus promote the conversion of biomass into aromatics.

The Interplay between Kinetics and Thermodynamics in Furan Diels-Alder Chemistry for Sustainable Chemicals Production

Biomass‐derived furanic platform molecules have emerged as promising building blocks for renewable chemicals and functional materials. To this aim, the Diels–Alder (DA) cycloaddition stands out as a versatile strategy to convert these renewable resources in highly atom‐efficient ways. Despite nearly a century worth of examples of furan DA chemistry, clear structure–reactivity–stability relationships are still to be established. Detailed understanding of the intricate interplay between kinetics and thermodynamics in these very particular [4+2] cycloadditions is essential to push further development and truly expand the scope beyond the ubiquitous addend combinations of electron‐rich furans and electron‐deficient olefins. Herein, we provide pertinent examples of DA chemistry, taken from various fields, to highlight trends, establish correlations and answer open questions in the field with the aim to support future efforts in the sustainable chemicals and materials production.

Valorisation of 2,5-dimethylfuran over zeolite catalysts studied by on-line FTIR-MS gas phase analysis

The valorisation of 2,5-dimethylfuran over zeolites under catalytic fast pyrolysis conditions was analysed by on-line FTIR-MS. BTX and olefins correlate and decrease with time on stream, whereas the isomerisation of 2,5-dimethylfuran increases.

Regeneration of pristine HZSM-5 extrudates during the production of deeply deoxygenated bio-oil from ex situ catalytic fast pyrolysis of biomass in a bench-scale fluidised-bed reactor

Deeply deoxygenated bio-oil with ∼1 wt% oxygen is produced in ex situ catalytic fast pyrolysis applying an unmodified HZSM-5 with good regeneration performance.

Thermo-catalytic co-pyrolysis of ironbark sawdust and plastic waste over strontium loaded hierarchical Y-zeolite

The objective of this research is to synthesize hierarchical strontium loaded Y-zeolite and study its application for ironbark (IB) and plastic waste (PW) co-pyrolysis. Commercial parent Y-zeolite (Si/Al = 2.48) was modified via sequential dealumination-desilication using citric acid and NaOH. Further, strontium (8 wt %) was loaded into the modified Y-zeolite via wet and dry impregnation methods. The prepared catalyst was characterized by N₂ adsorption-desorption isothermal, field emission scanning electron microscopy (FESEM) combined with energy dispersive x-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Thermogravimetric analyzer (TGA). After dealumination (treatment using 0.1 M of citric acid), the external surface area and Si/Al ratio increased from 53.5 to 147.4 m²/g and 2.48 to 5.36, respectively. However, the sequential desilication treatment reduced Si/Al ratio from 5.36 to 2.57. In addition, Y-zeolite enhanced the total aromatic percentage and reduced the acidic group in co-pyrolysis oil.

On-Line Composition Analysis of Complex Hydrocarbon Streams by Time-Resolved Fourier Transform Infrared Spectroscopy and Ion-Molecule Reaction Mass Spectrometry

On-line composition analysis of complex hydrocarbon mixtures is highly desirable to determine the composition of process streams and to study chemical reactions in heterogeneous catalysis. Here, we show how the combination of time-resolved Fourier transform infrared spectroscopy and ion-molecule-reaction mass spectrometry (IMR-MS) can be used for compositional analysis of processed plant biomass streams. The method is based on the biomass-derived model compound 2,5-dimethylfuran and its potential catalytic conversion to valuable green aromatics, for example, benzene, toluene, and xylenes (BTX) over zeolite β. Numerous conversion products can be determined and quantified simultaneously in a temporal resolution of 4 min^-1 without separation of individual compounds. The realization of this method enables us to study activity, selectivity, and changes in composition under transient reaction conditions. For example, increasing isomerization of 2,5-dimethylfuran to 2,4-dimethylfuran, 2-methyl-2-cyclopenten-1-one, and 2-methyl-2-cyclopenten-1-one is observed as the catalyst is exposed to the reactant, while BTX and olefin formation is decreasing.

Heterogeneous Diels-Alder tandem catalysis for converting cellulose and polyethylene into BTX

Producing biomass-derived aromatic hydrocarbons via controllable Diels-Alder reactions is a promising approach to recover energy and chemicals from waste streams. A tandem Diels-Alder catalysis consisting of SAPO-34 and Fe/HZSM-5 (stacked catalysis or mixed catalysis) was evaluated for thermochemical conversion of cellulose and polyethylene blends into benzene, toluene, and xylenes (BTX). Aromatization catalyst type significantly affected the activity of tandem catalysis, and the BTX obtained from the HZSM-5 stacked catalysis was ~2.3 times higher than that of the USY stacked one. An introduction of Fe active promoters into HZSM-5 increased the Lewis to Brønsted acid sites molar ratio (L/B) from 0.4 to 4.1. The comparison between Fe/HZSM-5 stacked catalysis and parent HZSM-5 single catalysis indicated that the former was more effective for BTX production, obtaining a nearly two-fold increase in yield with a high selectivity of 82.8%. A close proximity between Fe/HZSM-5 and SAPO-34 in the mixed catalysis increased the BTX enhancement to 1.8. A synergistic effect was provided by the coordination of Lewis and Brønsted acid sites in the Fe/HZSM-5 mixed catalysts for facilitating BTX generation, achieving a maximum of 25.9% at a Fe/HZSM-5 to SAPO-34 mass ratio of 1:1 with a theoretical L/B of 7.2. This work provides a sustainable strategy to produce biomass-derived aromatic hydrocarbons.

Pore Blocking by Phenolates as Deactivation Path during the Cracking of 4-Propylphenol over ZSM-5

Cracking of propyl side chains from 4-propylphenol, a model compound for lignin monomers, is studied for a commercial ZSM-5 zeolite catalyst. The decline of 4-propylphenol conversion with time on stream can be delayed by co-feeding water. FTIR spectroscopy shows the formation of chemisorbed phenolates during reactions and significant amounts of phenolics are detected by GC-MS of the extract from the spent catalysts. Thus, chemisorbed phenolates are identified as the main reason for deactivation in the absence of water. Regardless of the amount of co-fed water, substituted monoaromatics and polyaromatic species are formed. Comprehensive characterization of the spent catalysts including Raman and solid-state 27Al NMR spectroscopy, and thermogravimetric analysis points to a combination of deactivation processes. First, phenolates bind to Lewis acid sites within the zeolite framework and hinder diffusion unless they are hydrolyzed by water. In addition, light olefins created during the cracking process react to form a polyaromatic coke that deactivates the catalyst more permanently.

Catalytic upgrading of Quercus Mongolica under methane environment to obtain high yield of bioaromatics

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.

Integrated harvest of phenolic monomers and hydrogen through catalytic pyrolysis of biomass over nanocellulose derived biochar catalyst

The remarkable enhancement of phenolic monomer generation and hydrogen was achieved through catalytic pyrolysis of Douglas fir over nanocellulose derived biochar catalyst for the first time. The main compositions of produced bio-oil were phenolic monomers, furans, and naphthalenes, etc., in which the phenolic monomers were dominant compositions. And at the temperature of 650 °C and 3 of biochar to biomass ratio, the quantification results showed that the concentration of phenol was increased to 53.77 mg/mL from 15.76 mg/mL of free of biochar catalyst. The concentration of cresols were facilitated to 44.51 mg/mL from 20.95 mg/mL, while the concentration of dimethylphenols reduced to 7.76 mg/mL from 9.11 mg/mL. Up to 85.32 vol% of hydrogen was observed, increasing from 45.53 vol% of the non-catalytic process. After 15 cycles of reuse, biochar catalysts still favored to produce a much higher concentration of phenolic monomers and hydrogen than that of absence of biochar catalysts.

Catalytic pyrolysis of poplar sawdust: Excellent hydrocarbon selectivity and activity of hollow zeolites

Hollow zeolites were investigated for catalytic fast pyrolysis (CFP) of biomass to produce hydrocarbon-rich bio-oil. A series of hollow ZSM-5 catalysts were synthesized via a dissolution-recrystallization strategy. The physicochemical properties of the catalysts were investigated by high-resolution transmission electron microscopy, N₂ sorption, X-ray photoelectron spectroscopy, and ammonia temperature-programmed desorption experiments. The hollow zeolite was effective for increasing the hydrocarbon fraction in bio-oil. In particular, hollow HS-ZSM-5(50) afforded the highest hydrocarbon yield (6.8 wt%), which was ~3 times of that achieved with solid ZSM-5(50). The hollowness, acidity, and the presence of secondary wall mesopores in the hollow zeolite were found to affect bio-oil production. The hollow regions stabilized more active biomass intermediates and inhibited their repolymerization to coke, while the interior acid sites continually converted these intermediates to aromatic hydrocarbons. Secondary wall mesopores compromise the hollow space and hinder consecutive catalysis, resulting in phenols as the main product.

The Effect of Ni-ZSM-5 Catalysts on Catalytic Pyrolysis and Hydro-Pyrolysis of Biomass

With the demand of energy and re-utilization of wastes, the renewable lignocellulosic biomass, has attracted increasing and significant attention for alleviating the growing energy crisis and environment problems. As main components of lignocellulosic biomass, lignin, cellulose, and hemicellulose are connected by hydrogen bond to form a compact skeleton structure, resulting the trenchant condition of biomass pyrolysis. Also, pyrolysis products of above three main constituents contain a large amount of oxygenates that cause low heating value, high corrosiveness, high viscosity, and instability. Meanwhile, zeolites are of considerable significance to the conversion of lignocellulosic biomass to desirable chemical products on account of fine shape selectivity and moderate acid sites and strength. Among numerous zeolites, ZSM-5-based catalysts have been most extensively studied, and the acidity and porosity of ZSM-5 can be tuned by changing the content of Si or Al in zeolite. Beyond that, doping of other metal elements, such as Mn, Co, Ni, Ga, Ce, Pt, into ZSM-5 is also an efficient way to regulate the strength and density of acid sites in zeolite precisely. This review focused on the recent investigation of Ni-modified microporous ZSM-5 used in catalytic pyrolysis of lignin and cellulose. The application of metal-modified hierarchical ZSM-5 is also covered.

Effect of Montmorillonite clay on pyrolysis of paper mill waste

The thermal degradation of paper mill waste (PMW) has been investigated in presence and absence of Montmorillonite clay in the temperature range of ambient to 1000 °C and at the heating rates of 20 °C/min, 25 °C/min and 30 °C/min. Proximate and ultimate analyses and evaluation of calorific value (HHV) of PMW have been carried out using standard protocols. The thermo-gravimetric analysis (TGA) and differential thermogravimetric (DTG) data obtained under both situations have been used to evaluate the kinetic and thermodynamic parameters and elucidate the reaction mechanism. The clay has also been characterized using TGA/DTG analysis, Fourier Transform Infra-Red (FTIR) spectroscopic analysis and X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS), and scanning electron microscopic (SEM) techniques. The activation energy, pre-exponential factor and thermodynamic parameters have been evaluated using the model-free iso-conversional method of Flynn-Wall-Ozawa (FWO) and Vyazovkin and the distributed activation energy model (DAEM). The Montmorillonite clay has influenced the degradation process appreciably through its catalytic action.

Catalytic Pyrolysis of Tetra Pak over Acidic Catalysts

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).

Biochar as a catalytic material for the production of 1,4-butanediol and tetrahydrofuran from furan

Biomass valorization is emerging as a new trend for the synthesis of materials for various environmental applications. In this connection, a biochar resulting from pyrolysis of rice straw was employed as a catalytic material for the conversion of hemicellulose-derived furan into value-added platform chemicals such as 1,4-butanediol (1,4-BD) and tetrahydrofuran (THF). The biochar was used as catalyst support of bifunctional Ru-Re catalyst. Two different catalysts were prepared: a conventional activated carbon (AC)-supported Ru-Re catalyst (Ru-Re/AC) and a biochar-supported Ru-Re catalyst (Ru-Re/biochar). The Ru-Re/biochar had a different form of Re species from the Ru-Re/AC, resulting in different reducibility. The difference of reducibility between the two was attributed to alkali metal present in the biochar such as potassium. The Ru-Re/biochar had a 17 times lower metal dispersion on the surface than the Ru-Re/AC, ascribed to a lower surface area of the biochar than the AC. Catalytic activities of the catalysts with regard to reaction rate per available surface active site for transforming furan to 1,4-BD and THF were measured. The Ru-Re/AC was 3 times less active than the Ru-Re/biochar. This study not only provides a way to efficiently use biomass both for environmental catalysts and for feedstock of producing value-added platform chemicals, but also shows potential of biochar for the replacement of typical catalysts employed in biorefinery.

Microwave-assisted catalytic upgrading of co-pyrolysis vapor using HZSM-5 and MCM-41 for bio-oil production: Co-feeding of soapstock and straw in a downdraft reactor

Microwave-assisted co-pyrolysis of low hydrogen-to-carbon and high hydrogen-to-carbon effective ratio materials with the aid of HZSM-5 and MCM-41 is a promising technique to improve the bio-oil quality. The low content of hydrocarbons and short life cycle of catalyst limit the application of pyrolysis technology in biomass energy conversion. The effects of catalytic temperature, and HZSM-5-to-MCM-41, feedstock-to-catalyst, and straw-to-soapstock ratios on the yield and composition of bio-oil were studied in this work. The quality of bio-oil during biomass pyrolysis can be improved by adjusting the operating conditions. The optimal catalytic temperature, and ratios of HZSM-5-to-MCM-41, feedstock-to-catalyst, and straw-to-soapstock were 400 °C, 1:1, 2:1, and 1:2, respectively. The addition of MCM-41 was beneficial in prolonging the life of HZSM-5 since the macromolecular compounds cracked when MCM-41 was added which restrain the generation of coke. The co-pyrolysis of soapstock with straw advanced the deoxygenation of oxygen-containing compounds especially phenol from straw during pyrolysis.

Co-pyrolysis of biomass and plastic waste over zeolite- and sodium-based catalysts for enhanced yields of hydrocarbon products

Ex-situ co-pyrolysis of sugarcane bagasse pith and polyethylene terephthalate (PET) was investigated over zeolite-based catalysts using a tandem micro-reactor at an optimised temperature of 700 °C. A combination of zeolite (HZSM-5) and sodium carbonate/gamma-alumina served as effective catalysts for 18% more oxygen removal than HZSM-5 alone. The combined catalysts led to improved yields of aromatic (8.7%) and olefinic (6.9%) compounds. Carbon yields of 20.3% total aromatics, 18.3% BTXE (benzene, toluene, xylenes and ethylbenzene), 17% olefins, and 7% phenols were achieved under optimal conditions of 700 °C, a pith (biomass) to PET ratio of 4 and an HZSM-5 to sodium carbonate/gamma-alumina ratio of 5. The catalytic presence of sodium prevented coke formation, which has been a major cause of deactivation of zeolite catalysts during co-pyrolysis of biomass and plastics. This finding indicates that the catalyst combination as well as biomass/plastic mixtures used in this work can lead to both high yields of valuable aromatic chemicals and potentially, extended catalyst life time.

Two-way desorption coupling to enhance the conversion of syngas into aromatics by MnO/H-ZSM-5

We herein report a composite catalyst containing partially reducible and highly active manganese oxide and nano-size H-ZSM-5 with short b-axis, prepared for the direct conversion of syngas into aromatics.

From cellulose to 1,2,4-benzenetriol via catalytic degradation over a wood-based activated carbon catalyst

1,2,4-Benzenetriol was obtained from cellulose hydrothermal degradation using phosphoric acid-activated wood-based AC as the catalyst.

Renewable aromatics through catalytic flash pyrolysis of pineapple crown leaves using HZSM-5 synthesized with RHA and diatomite

The influence of reactor temperature of 300  and 600 °C and the acidity of the ZSM-5 and HZSM-5 catalysts on the pyrolysis product yields of the pineapple crown leaves have been investigated in a fixed bed reactor Py-GC/MS. The ZSM-5 catalyst was hydrothermally synthesized with a Si/Al ratio 50, using residual diatomite and rice husk ash as alternative sources of Al and Si for catalyst cost reduction. For the HZSM-5 synthesis, calcined ZSM-5 was activated by ion exchange between Na⁺ and H⁺. The catalysts structure was confirmed by the XRD and Rietveld treatment, SEM, FTIR, FRX, TGA and BET results. Analytical pyrolysis of the biomass was carried out at 500 °C in a Py-5200 HP-R pyrolyzer connected to the GC/MS and the pyrolysis vapors were transported to a catalytic bed at 300 and 600 °C. The results showed that the increase in the catalytic bed temperature promoted increased the aromatic content. The main pyrolysis products of the PCL were oxygenated compounds that were converted at 600 °C using the HZSM-5 catalyst into high value renewable aromatic compounds for the chemical industry, such as benzene, toluene, xylene, etilbenzene, thereby confirming the deoxygenation activity of synthesized catalyst to produce renewable aromatics compounds which are important platform chemicals and precursors for jet fuels, gases, polymers and solvents.

Monocyclic aromatic hydrocarbons production from catalytic cracking of pine wood-derived pyrolytic vapors over Ce-Mo2N/HZSM-5 catalyst

A series of Mo₂N/HZSM-5 and transition metal modified Mo₂N/HZSM-5 catalysts were prepared for the catalytic upgrading of pine wood-derived pyrolytic vapors for the selective production of monocyclic aromatic hydrocarbons (MAHs), while restraining the formation of polycyclic aromatic hydrocarbons (PAHs). Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed to determine the effects of several factors on selective MAHs production, including Mo₂N loading on HZSM-5, transition metal (Fe, Ce, La, Cu, Cr) modification of Mo₂N/HZSM-5, pyrolysis temperature, and catalyst-to-biomass ratio. In addition, quantitative experiments were conducted to determine the actual yields of major aromatic hydrocarbons and the source of aromatic hydrocarbons from basic biomass components. Results indicated that among the various catalysts, the Ce-10%Mo₂N/HZSM-5 exhibited the best performance on promoting the formation of MAHs and restraining the generation of PAHs. Under the optimal conditions, the actual yields of MAHs and PAHs from Ce-10%Mo₂N/HZSM-5 catalytic process were 99.8mg/g and 7.5mg/g, while those from HZSM catalyst were only 77.2mg/g and 23.7mg/g respectively. Furthermore, the possible catalytic mechanism of the Ce-Mo₂N/HZSM-5 catalyst was proposed based on the catalyst characterization.

Catalytic fast pyrolysis of a wood-plastic composite with metal oxides as catalysts

The catalytic fast pyrolysis of a poplar wood-polypropylene composite (WPP) was investigated using Py-GC/MS in the presence of ZnO, CaO, Fe₂O₃ and MgO. The synergistic effects between wood and plastic components in both non-catalytic and ZnO-catalyzed pyrolysis of WPP were studied. CaO facilitated the removal of oxygen due to its strong basicity, eliminating carboxylic acids and phenols from the products, while slightly increasing cyclopentanones and alkenes. MgO has weaker deoxygenation but stronger chain scission activities versus CaO, and significantly enhanced the alkene yields. Alkene yields were highest using ZnO among the four catalysts. ZnO increased ketone and phenol yields while reducing carboxylic acids. Aromatics were identified in the presence of Fe₂O₃. A synergistic effect between poplar wood and PP in the uncatalyzed pyrolysis of WPP increased the yields of carboxylic acids, phenols and light alkenes, while it reduced carbonyl-containing oxygenates such as aldehydes, ketones and furans. The synergy in the ZnO-catalyzed pyrolysis of WPP further enhanced the formation of monomeric phenols and alkenes.

Direct catalytic co-conversion of cellulose and methane to renewable petrochemicals

Direct catalytic co-aromatization of cellulose and methane to renewable petrochemicals over supported Zn catalysts.

Exploratory catalyst screening studies on the liquefaction of model humins from C6 sugars

A catalyst screening study is reported on the liquefaction of humins, the solid byproducts from C6 sugar biorefineries for levulinic acid and 5-hydroxymethylfurfural production.