Catalytic Cracking of Biomass-Derived Hydrocarbon Tars or Model Compounds To Form Biobased Benzene, Toluene, and Xylene Isomer Mixtures

Abstract

The gasification of biomass is one of the most prominent technologies for the conversion of the raw material feedstock to polymers, useful chemical substances, and energy. The main engineering challenge during the processing of wastes is the presence of tars in gaseous reaction products, which could make this operation methodology unsuccessfully due to the blockage of separating particle filters, fuel line flow, and substantial transfer losses. Catalytic hydrocarbon cracking appears to be a promising developing approach for their optimal removal. However, it is still highly desirable to enhance the catalysts’ activity kinetics, selectivity, stability, resistance to (ir)­reversible coke deposition, and regeneration solutions. The purpose of this Review is to provide a comparative systematic evaluation of the various natural, synthetic, and hybrid ways to convert the model molecular compounds into benzene, toluene, xylene, (poly)­aromatics, syngas, and others. The recent scientific progress, including calcite, dolomite, lime, magnesite, olivine, char, nonmetallic activated carbons, supported alkali, noble, and transition metals, and (metal-promoted) zeolites, is presented. A special concentrated attention is paid to effectiveness, related to hydrogenation, peculiar pore structure, and formulations’ suitable acidity. The role of catalysis is described, recommendations for prospective catalyzed mechanisms are provided, and future technical feasibility is discussed as well.

Metal-Supported Biochar Catalysts for Sustainable Biorefinery, Electrocatalysis, and Energy Storage Applications: A Review

“…Thus, the removal and/or mitigation of tar is a critical step to commercialize the biomass reforming/gasification process for syngas production. Dolomite, olivine, nickel, alkali metals are commonly used catalysts for tar cracking [56]. However, these conventional catalysts suffered from deactivation arising from coking and poisoning during the process.…”

Sewage sludge ashes as a primary catalyst for the abatement of tar in biomass gasification: Bubbling versus spouted‐fluidized bed configuration

“…[ 1 ] Different types of natural (e.g., mineral catalysts such as dolomite, calcite, magnesite, olivine, clay minerals, and sea shells) and synthetic catalysts (i.e., carbon‐supported catalysts, noble‐metal‐based catalysts, alkali metal catalysts, transition metal catalysts, zeolites, and metal‐promoted zeolite catalysts) have been tested over the last decades for both in situ and downstream tar treatments. [ 4–6 ] The advantages and disadvantages of the different types of catalysts are described in detail in Kostyniuk et al [ 4 ] In general, natural mineral catalysts are relatively cheap, abundant, and disposable, but their catalytic activities are poorer than those of the synthesized catalysts. Moreover, they are characterized by particularly low mechanical strength, which hinders their use in fluidized bed (FB) reactors.…”

“…Moreover, they are characterized by particularly low mechanical strength, which hinders their use in fluidized bed (FB) reactors. [ 4 ]…”

Syngas Production From Palm Kernel Shells With Enhanced Tar Removal Using Biochar From Agricultural Residues†

“…Several studies showed that additional thermal cracking reactions of the hot syngas with the aid of steam or catalysts could significantly decrease the tar components from syngas (Bonilla et al, 2019). The process involves chemical reactions to transform tar components into high heating value gaseous components, such as oxygen/sulfur-containing hydrocarbon, aromatic compounds, and polynuclear aromatic hydrocarbons (PAHs) (Kostyniuk et al, 2019). The decomposition of tar involves complex reaction pathways associated with the presence of hydrocarbon compounds.…”