Catalytic Conversion of Furan to Hydrocarbons using HZSM‐5: Coking Behavior and Kinetic Modeling including Coke Deposition

Abstract

Coke deposition is the biggest barrier that hinders the hydrocarbon yields during the catalytic pyrolysis of biomass. The proposed pathway studied here yields benzofuran as a primary product, all the olefins and aromatic hydrocarbons as secondary products, and polycyclic aromatic hydrocarbons as tertiary products. The product selectivity only changed with catalytic temperature and coke deposition, whereas no effect was observed if the weight hourly space velocity and partial pressure were varied. The curve of conversion versus coke content in the catalytic conversion of furan follows an exponential trend [i.e., Φ=exp(‐αC)] which indicates that the catalytic conversion of furan exhibits fast deactivation. A kinetic model considering coke deposition has been built based on the above reaction pathway to correlate the product distribution with the coke content, and the final correlation coefficients (>0.96) indicate good agreement.

Coke Formation during Thermal Treatment of Bio-oil

“…Because of the low quality of bio-oil including high acidity, instability, low energy content, high water and oxygen contents, etc., it cannot be used directly in engines as a fuel. ,− Catalytic pyrolysis was thus investigated to improve the properties of bio-oil by passing the volatiles produced in the pyrolysis over a catalyst for their in situ upgrading. ,− However, the specifications of the bio-oil produced still were not in the range for the use in vehicles. ,− In addition, coke formation during catalytic pyrolysis was a bottleneck in this process, which could reduce the carbon yield from biomass, deactivate the catalyst, plug the catalyst bed and consequently prevent the process from continuous operation. ,− As a result, a considerable number of pieces of research were performed to study the mechanism for coke formation and the methods for preventing the formation of coke. ,,,,,− …”

Catalytic conversion of furanic compounds over Ga-modified ZSM-5 zeolites as a route to biomass-derived aromatics

“…1424 The product distribution also strongly varies with the contact time. 25 Despite the recognized potential of CFP, there is a lack of detailed understanding about the reaction mechanism, which hampers the design of better catalysts with a higher BTX selectivity and a lower rate of coke formation. A specific challenge is rapid catalyst deactivation due to deposition of carbonaceous deposits in the zeolite micropores.…”

Enhancing the Synergistic Effect of Cellulose and Polypropylene for Petrochemical Production during Catalytic Fast Pyrolysis by Mesoporous Gallium-MFI Zeolites

“…17,19,32,60 As shown in Figure 6, this reaction pathway can provide a shortcut to produce aromatic hydrocarbons with a higher carbon yield than the pathways through which aromatics are produced during CFP of cellulose and PP individually. 13,27,61 For example, during CFP of cellulose and PP individually, the formation of aromatics must proceed through several common reaction steps: (i) thermal cracking of the polymer structures to primary pyrolysis products, e.g., furans and branched olefins, (ii) catalytic cracking (and deoxygenation) of the primary pyrolysis products to small olefins (e.g., C 2 −C 5 olefins), (iii) oligomerization of the small olefins to C 6 −C 10 olefins, (iv) transformation of C 6 −C 10 olefins to dienes through hydride transfer reactions, and (v) cyclization and aromatization of the dienes to aromatics. 13,27,61−64 In comparison, the Diels−Alder reaction of furans with olefins can cause a change in the deoxygenation pathways of furans from mainly decarbonylation and decarboxylation during CFP of cellulose to dehydration during cofeed CFP of cellulose and PP.…”

“…Lignocellulosic biomass has been considered an attractive feedstock for producing renewable petrochemicals, because of its low cost and abundance. , Producing petrochemicals from biomass can help to preserve the limited petroleum reserves, meet increasing market demand, and mitigate the environmental challenges of greenhouse emissions. − To date, many conversion technologies have been developed to convert lignocellulose to petrochemicals. − Among them, the catalytic fast pyrolysis (CFP) of lignocellulose with zeolite catalysts (e.g., ZSM-5) has gained increasing attention, because this process can directly convert lignocellulose to valuable petrochemicals (e.g., benzene, toluene, xylenes, ethylene, and propylene) in a single reactor and in a short time (e.g., in seconds or minutes). ,, However, because lignocellulosic biomass is rich in oxygen (typically >40 wt %) and poor in hydrogen (∼6–7 wt %), high yields of solid residues (char/coke) are generated during the CFP of lignocellulose. , The high yields of solid residues (usually >30 C%) decrease the carbon efficiency of petrochemical products and can cause rapid catalyst deactivation. , …”

“…1,11,12 However, because lignocellulosic biomass is rich in oxygen (typically >40 wt %) and poor in hydrogen (∼6−7 wt %), high yields of solid residues (char/ coke) are generated during the CFP of lignocellulose. 13,14 The high yields of solid residues (usually >30 C%) decrease the carbon efficiency of petrochemical products and can cause rapid catalyst deactivation. 14,15 To enhance petrochemical production and reduce solid residue formation, researchers have tried cofeeding lignocellulosic biomass with hydrogen-rich plastic wastes during CFP.…”