Enhancement of catalytic activity for toluene disproportionation by loading Lewis acidic nickel species on ZSM-5 zeolite

Abstract

Impregnation of various heteroelements on the ZSM-5 zeolite was applied to improvement of the catalytic activity in toluene disproportionation. Nickel loaded on ZSM-5 (Ni/ZSM-5) exhibited higher catalytic activity (toluene conversion) and lower benzene / xylene ratio (closer to the stoichiometry, meaning low rate of side reaction) than H-ZSM-5 zeolite. The Ni/ZSM-5 with Ni/Al = 0.6 showed the maximum in catalytic activity, and excess Ni loading caused decrease in the conversion and increase in the benzene / xylene ratio due to decrease of acid amount and acceleration of dealkylation, respectively. The detailed analysis of acidic property by means of 2 ammonia IRMS-TPD method showed that the Ni loading generated Lewis acid sites on the zeolite. The synergy of Brønsted and Lewis acid sites, ascribed to Si-OH-Al and Ni species, respectively, is suggested to give the high activity of desired reaction.

Kinetic Study of Seed-Assisted Crystallization of ZSM-5 Zeolite in an OSDA-Free System Using a Natural Aluminosilicate as Starting Source

“…This solid displayed a nitrogen adsorption isotherm of type I (Figure 2), giving information for the reorganization of the amorphous structure of Perlite into a microporous framework. 28,29 The hydrothermal treatment of Perlite generates a microporous material with a specific surface of 290 m 2 •g −1 . Textural properties shown in Table 1 are in good agreement with those reported elsewhere for a ZSM-5 zeolite.…”

Constructing single-crystalline hierarchical plate-like ZSM-5 zeolites with short b-axis length for catalyzing MTO reactions

“…ZSM-5 is a zeolite with MFI topological structure that has main mass transportation straight channels (5.3 Å × 5.6 Å) along the b-axis and sinusoidal channels (5.1 Å × 5.5 Å) along the a-axis. 1 The zeolite has been widely used as a catalyst in many industrial processes such as catalytic cracking, 2 toluene disproportionation, 3,4 and methanol-to-olefin (MTO) reactions. 5,6 In these catalytic processes, although some reactions benefit from the specific channels of the zeolite to achieve a shape-selective catalytic effect, 3,4 for more reactions, the diffusion restriction inherited from the sole micropores and long diffusion path in zeolites makes it difficult to exert intrinsic catalytic performance of zeolites, especially if bulky reactants or products are involved.…”

“…1 The zeolite has been widely used as a catalyst in many industrial processes such as catalytic cracking, 2 toluene disproportionation, 3,4 and methanol-to-olefin (MTO) reactions. 5,6 In these catalytic processes, although some reactions benefit from the specific channels of the zeolite to achieve a shape-selective catalytic effect, 3,4 for more reactions, the diffusion restriction inherited from the sole micropores and long diffusion path in zeolites makes it difficult to exert intrinsic catalytic performance of zeolites, especially if bulky reactants or products are involved. [5][6][7][8] In principle, there are three approaches to solve the diffusion limitation problem: (1) decreasing the crystal size of zeolites to shorten the intracrystalline diffusion path of reaction participants.…”

Study of Catalytic Properties of the HoxMg1-xAl2O4 Modified HZSM-5 Zeolite in Conversion of Methanol to C2-C4 Alkenes and p-Xylene

“…In this regard, the formation of light alkenes and pxylene on catalysts based on zeolite ZSM-5 is the most promising direction. Xylenes, especially p-xylene, are valuable intermediates for the production of terephthalic acid, polyethylene terephthalate, fibers, plasticizers and other valuable products [21][22][23][24]. The demand for light C2-C4 alkenes and para-substituted aromatic hydrocarbons grows steadily every year.…”