Boosting the synthesis of value-added aromatics directly from syngas via a Cr₂O₃ and Ga doped zeolite capsule catalyst

Abstract

The single-pass conversion of syngas into para-xylene was realized using a bifunctional catalyst Cr2O3/Ga-ZSM-5@SiO2. The Ga species facilitates the methanol consumption process by C–C coupling optimization, enhancing the yield of the target aromatics.

Construction of HZSM-5 with a Mesoporous Structure and Suitable Acidity: Application in Catalytic Syngas Conversion to Light Aromatics over Na–FeMn/HZSM-5 Zeolite

“…Aromatics, particularly light aromatics, which include benzene, toluene, ethylbenzene, and xylenes (BTEX), play a vital role in the current industry and are extensively used as synthetic materials for resins, rubbers, medicine, pesticides, and pigments. , Industrial production of light aromatics is mainly dependent on the oil-processing route. , However, because of the limitation of fossil oil reserves and the increasing demand for aromatics, a replaceable pathway to produce light aromatics from nonpetroleum resources is highly necessary. − It is widely recognized that syngas conversion into high-value aromatics is mainly realized via the methanol-mediated (SMA) or Fischer–Tropsch synthesis (FTS) pathways over oxide-based/HZSM-5 composite catalysts. − The SMA route consists of syngas conversion to methanol over oxide-based catalysts (Cu-, In-, and Zr-based catalysts) and the subsequent aromatization of methanol over HZSM-5 zeolite. − Generally, this route can achieve high aromatics selectivity (∼70%), but the selectivity of the byproduct CO 2 is up to 40%, and CO conversion (∼20%) is not undesirable. , As for the FTS pathway, Fe-based/HZSM-5 is the most widely used catalyst, over which CO is first hydrogenated into lower olefins on iron carbide, and then lower olefins are transformed into aromatics on HZSM-5 . Compared to the SMA route, CO conversion can be significantly increased to 90% with a relatively lower CO 2 selectivity of 20%, but the overall aromatics selectivity can still remain at 60%. − In addition, raw materials of Fe-based catalysts are usually cheaper and more abundant than methanol synthesis catalysts and have higher mechanical strength.…”

“…Aromatics, particularly light aromatics, which include benzene, toluene, ethylbenzene, and xylenes (BTEX), play a vital role in the current industry and are extensively used as synthetic materials for resins, rubbers, medicine, pesticides, and pigments. 1,2 Industrial production of light aromatics is mainly dependent on the oil-processing route. 3,4 However, because of the limitation of fossil oil reserves and the increasing demand for aromatics, a replaceable pathway to produce light aromatics from nonpetroleum resources is highly necessary.…”

“…33 Tsubaki et al adjusted the acidity of zeolite to enhance paraxylene selectivity by sealing external acid sites of zeolites. 1,29 The diffusion efficiency of molecules has a great effect on the distribution of aromatics and the stability of zeolites. 34−36 Fast mass transportation of aromatics is beneficial to generate more light aromatics and avoid the formation of more heavy aromatics, which can decrease coke deposition at the active sites, slowing down the decline of aromatization ability.…”

“…Pidko et al fabricated bimetallic Ca- and Ga-modified HZSM-5, and it was found that a small amount of Ca contributed to optimizing the MTA process . Tsubaki et al adjusted the acidity of zeolite to enhance para-xylene selectivity by sealing external acid sites of zeolites. , …”

Synthesis of durene by methylation of 1,2,4-trimethylbenzene with syngas over bifunctional CuZnZrOx–HZSM-5 catalysts

“…7 The syngas-to-hydrocarbon process is considered one of the most important non-petrochemical routes capable of converting coal, natural gas, and biomass into liquid fuels, aromatics, and C 2+ oxygenated compounds. 8,9 To alleviate the high demand for petroleum feedstocks, Chang et al [10][11][12][13] proposed the direct conversion from syngas to aromatics by employing active metals and zeolites as bifunctional catalysts. In recent years, many research teams have directly synthesized durene or tetramethylbenzene using syngas as platform molecules.…”