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HZSM-5@silicalite-1 catalysts were prepared by the hydrothermal method, and the structure, morphology, acidity and pore texture of core–shell catalysts were studied by XRD, SEM, TEM, NH3-TPD, Py-IR and N2 adsorption/desorption isotherms in detail. Their catalytic performances were tested in the alkylation reaction of toluene with methanol. The results showed that a coating layer was formed in the form of silicalite-1 on HZSM-5. NH3-TPD measurements indicated that HZSM-5@silicalite-1 contained less strong acid sites but more weak acid sites than the parent HZSM-5. The selectivity of p-xylene for toluene alkylation was approximately linear with the percentage of weak acid in total acid. Under the optimal reaction conditions, the conversion of toluene was 34.15%, and the selectivity of p-xylene was 96.77%. [ABSTRACT FROM AUTHOR]

Mordenite (MOR) has demonstrated potential as a catalyst for alkylation due to high variability, intrinsic porosity, and outstanding stability. However, the contact probability of benzene and methanol has been limited by typical layered structures of MOR and there is no connection between layers. Here, we report the preparedness of H‐MOR via a sequential post‐treatment method based on a commercial MOR. H‐MOR sample had appeared lattice imperfections inferred from characterization means. The samples were tested with benezene methylation reaction. Results show that the high conversion of benzene and the high selectivity of toluene were obtained from the miracle role of lattice imperfections in the H‐MOR sample. Sequentially, based on the study of all catalyst structure and physical properties, a plausible reaction mechanism for the selectivity of the desired toluene was proposed. [ABSTRACT FROM AUTHOR]

Background: The alkylation of benzene with methanol is an important synthetic method that is widely used in various chemical production processes. However, obtaining a high selectivity for xylene and annihilating the MTO side reaction remain challenges. Results: In this work, a Ru/HZSM-5 catalyst was prepared using ZSM-5 as the precursor by a chemical precipitation method. Both XRD and TEM confirmed that Ru nanoparticles were evenly dispersed on the surface of the ZSM-5. The catalytic performance of benzene alkylation with methanol on the Ru/HZSM-5 catalyst was investigated. The results showed that the Ru/HZSM-5 catalyst could completely annihilate the MTO side reaction with a high conversion efficiency of benzene and selectivity for xylene, which resulted from the large gap between the transgression energy value of Ru and the ionization potential value of benzene, and the acidity of the catalyst changed greatly. Conclusion: These findings may offer not only a new and efficient multifunctional catalyst for benzene alkylation but also fundamental insight into the catalytic mechanism of the Ru/HZSM-5 catalyst. [ABSTRACT FROM AUTHOR]

Abstract Normally, higher conversion of benzene represented higher utilization rate of methanol. Given these problems, we have modified HZSM-5 with 3-aminopropyltriethoxysilane (AMEO) and the physical-chemistry properties of the catalysts were characterized by XRD, Zeta potential, Contact Angle Measurement, SEM, NH 3 -TPD and EDS. Meanwhile, the influence of AMEO addition on the catalytic performance of HZSM-5 for the alkylation of benzene with methanol was researched. Results show that HZSM-5 treated with AMEO, not only the selectivity of target product and the utilization of methanol for the alkylation of benzene with methanol were improved, but also the amount of coke was significant reduced. Graphical abstract Unlabelled Image Highlights • DMCS20-HZSM-5 was investigated for benzene alkylation. • DMCS20-HZSM-5 exhibited the highest selectivity of PX. • DMCS20-HZSM-5 exhibited a high methanol utilization. • The quantity of coke was greatly decreased over DMCS20-HZSM-5. [ABSTRACT FROM AUTHOR]

The process of benzene/methanol alkylation reaction was studied thermodynamically based on functional group contribution method of Benson. Results show that ortho-xylene (OX), Ethyl-benzene (EB) and tri-methylbenzene (TMB) are the main byproduct in alkylation of benzene by methanol and the suppression of OX, EB and TMB over hierarchical porous HZSM-5 or other types of acidic solid catalysts still remains a great challenge. To overcome these limitations, we modified hierarchical ZSM-5 with ruthenium (Ru) to evaluate the alkylation of benzene with methanol in a fixed-bed continuous flow reactor. It was found that the presence of a small amount of Ru in ZSM-5 catalyst would largely suppress the formation of EB, reduce the selectivity of OX and TMB, and also extend greatly the live time of the catalyst. Alkylation of benzene by methanol: thermodynamics analysis for designing and designing for enhancing the selectivity of toluene and para-xylene.Graphical Abstract: Alkylation of benzene by methanol: thermodynamics analysis for designing and designing for enhancing the selectivity of toluene and para-xylene [ABSTRACT FROM AUTHOR]

The secondary reaction of toluene is difficult to be suppressed in benzene alkylation with methanol over conventional acidic zeolite catalysts. Moreover, the formation of coke yet remains a challenging problem. In this study, Na-Y zeolites were modified with ammonium carbonate (AC), citric acid (CA) and caesium nitrate(CN) to evaluate the alkylation of benzene with methanol, which was also characterized by XRD, SEM, FT-IR, N2 adsorption and Py-IR. For the Na-Y treated with AC-CA-CN, not only the catalytic selectivity for the alkylation of benzene with methanol was improved (the total selectivity of toluene and xylene was 97.9% and toluene selectivity was 86.4%), but also the quantity of coke was greatly decreased. [ABSTRACT FROM AUTHOR]