Selective Formation of Para-Xylene by Methanol Aromatization over Phosphorous Modified ZSM-5 Zeolites

Abstract

Phosphorous modified ZSM-5 zeolites were synthesized by incipient wetness impregnation. Their performances for the methanol to aromatics conversion (MTA) were subsequently evaluated and the relationship between the catalyst structure and performance was focused on. The obtained results indicated that the introduction of phosphorous resulted in the modification of the catalyst structure characteristics and acidic properties, i.e., the reduction in the external surface area and micropore volume, the narrowing of the pore size, and the decrease in the quantity and strength of acid sites. As a result, the P/HZSM-5 catalyst exhibited the enhanced selectivity for the para-xylene (PX) in xylene isomers and xylene in aromatics, and their increase degrees were intensified with the increasing P content. The selectivity of PX in X increased from 23.8% to nearly 90% when P content was 5 wt.%. Meanwhile, the selectivity of xylene in aromatics was enhanced from 41.3% to 60.2%.

Size controllable synthesis of ZSM-5 zeolite and its catalytic performance in the reaction of methanol conversion to aromatics

“…As shown in figure 12 b , the lifetime of the catalyst was reduced gradually with the increase of Zn loading. When the active Zn-Lewis acid sites were generated by the impregnation of Zn, the inactive ZnO clusters were also formed which has been reported in our previous studies [13,44]. These ZnO species dispersed on the surface or in the channels of ZSM-5 zeolites decreased the specific surface area and pore volume.…”

“…Although the selectivity of aromatic hydrocarbons was only about 30% over ZSM-5, the selectivity of aromatic hydrocarbons reached more than 90% after the impregnation with Zn. Introducing Zn into ZSM-5 could form the new Lewis acid sites and promote the methanol aromatization ability [ 13 , 18 , 45 ].…”

“…The reaction of methanol to hydrocarbons (MTHs) over a zeolite catalyst discovered in the 1970s is a non-petroleum route for the production of various hydrocarbons [9][10][11][12][13]. ZSM-5 zeolite is one of the most concerned materials in the MTH reaction.…”

Modification Strategy of ZSM-5 Zeolite for Enhancing p-Xylene Selectivity in Toluene Disproportionation

“…They are most promising as the versatile substances for catalysts production in petrochemical chemistry [9,10]. other applications are included environmental protection [11,12] and adsorption [13] because of special channel structure, high BET surface area, abundant acid sites and thermal and hydrothermal stability [14].…”

Toward the Mechanism of o-Xylene Isomerization in Selected Zeolites of Different Si/Al Ratios and Channel Sizes—Experiment Corroborated by Periodic DFT + D Simulations

“…The conversion of alcohols during the upgrading of natural resources (biomass and natural gas) to aromatics emerges as an interesting alternative of crude oil processing. 20,21 The conversion of methanol is investigated comprehensively, but also, ethanol conversion over acidic zeolites is gaining attention rapidly. 22−24 The ethanol conversion to the C 3+ hydrocarbons has been recognized to proceed through a dual-cycle mechanism 25 corresponding to the one established for the methanol-toolefin process.…”