Influence of Catalyst Binders on the Acidity and Catalytic Performance of HZSM-5 Zeolites for Methanol-to-Propylene (MTP) Process: Single and Binary Binder System

Abstract

The effect of the binders, such as silica, alumina, and aluminum phosphate solution (APS), was studied on the acidity and catalytic performance of HZSM-5 zeolite (SiO 2 /Al 2 O 3 = 80) in methanol-to-propylene (MTP) process. The strong acidity of catalyst increased slightly with alumina binder but decreased with silica and APS binders. It is noted that the catalyst with APS binder showed the highest bulk crush strength. Catalytic performance of the alumina or silica bound catalyst was comparable to that of pure HZSM-5 catalyst while that of APS bound catalyst was completely different depending on the binder content. Low content (10 wt%) of APS resulted in a dramatically enhanced propylene selectivity ([40 C mol%) due to the decrease in strong acidity. On the other hand with high content ([20 wt%) of APS, methanol was mostly dehydrated into dimethylether without further transformation into hydrocarbons even if the mechanical strength was significantly improved. The binary binder system was proposed not only to improve the mechanical strength of catalyst with small amount of APS binder but also to keep a high propylene selectivity. The catalyst bound with APS-and-alumina or APS-and-silica showed a comparable propylene selectivity to that of HZSM-5 with the 10 wt% of APS single binder while demonstrated much higher bulk crush strengths.

An Overview on Zeolite Shaping Technology and Solutions to Overcome Diffusion Limitations

“…Although the same phenomenon between silica from the binder and extra-framework species forming new Brønsted acid site occurred, the presence of sodium ions in LUDOX HS-40 (silica binder used) may have neutralized them. This was corroborated by Lee et al [12] after blending HZSM-5 zeolite with silica, alumina, and/or aluminophosphate solution together with hydroxylethylcellulose. Upon testing the samples in the conversion of methanol to propylene, they also reached the conclusion that the best procedure would be the addition of silica or alumina with aluminophosphate solution, conferring high bulk crush strength and similar propylene selectivity to that achieved over HZSM-5.…”

From powder to extrudate zeolite-based bifunctional hydroisomerization catalysts: on preserving zeolite integrity and optimizing Pt location

“…In the case of catalytic cracking, the reduction of the zeolite acidity can be beneficial conducing to a reduction of catalyst deactivation and so longer catalyst lifetimes [32,33]. Some cases of improved acidity following shaping processes are also documented in literature [35][36][37][38]. The characteristics of the binder and the shaping procedure play, hence, a vital role on the final properties of the zeolite [39], but for the same binder and shaping procedure different behaviours can also occur depending on the zeolite [40].…”

Dimethyl Ether to Olefins over Modified ZSM-5 Based Catalysts Stabilized by Hydrothermal Treatment

“…HZSM-5 is the general component of catalysts for olefin synthesis from oxygenates (dimethyl ether or methanol) [1]. Investigations of MTH (methanol-to-hydrocarbons) catalysts are focused on studying the effect of crystal size, the module of the HZSM-5 zeolite, binder type, dealumination degree, the presence of mesopores, and the physical chemical properties of catalyst, such as crystallinity, acidity, specific surface area, and the volume of micro-and mesopores [2][3][4][5][6][7][8]. The total number of works in the field of catalysts for propylene synthesis from methanol in the last 5 years has more than 200.…”