Ammonia pools effect in Cs modified X zeolites for side-chain alkylation of toluene with methanol

Investigating the Role of Cs Species in the Toluene–Methanol Side Chain Alkylation Catalyzed by CsX Catalysts

“…All samples exhibited two peaks, suggesting the presence of cesium in two chemical states. The Cs 3d 5/2 peak at 724.5 eV corresponds to the exchange cation Cs + , while the peak at 725.0~725.2 eV is attributed to the Cs 2 O phase [18]. As observed in the order of CsX_10, CsX_24, and CsX_31, the content of Cs + ions on the molecular sieve's surface and at a depth of 50 nm gradually increased (Table 3).…”

“…The majority of oxygen below the 50 nm surface is attributed to framework oxygen, while the remaining oxygen is likely associated with the highly dispersed Cs 2 O phase found in the inner cavities or pores of the X molecular sieve crystals. The O 1s BE of zeolite is correlated with the alkalinity of the framework oxygen, with its higher alkaline strength corresponding to lower O 1s BE values [18]. Notably, the O 1s BE peak positions in CsX are all approximately 530.9 eV, indicating a similar alkaline strength across different ion exchanges in CsX.…”

“…This could be because the strong basic sites that are active for the side chain alkylation reactions of toluene and methanol also catalyze the undesired methanol decomposition reaction at roughly 10 times the rate [13]. It is commonly accepted in the literature that an excess of Cs 2 O (a strongly basic site) may lead to the deep decomposition of methanol into CO [7,[18][19][20].…”

“…Based on the findings of Unland, Baker, Lin, and Sphon [16], the creation of styrene may be facilitated through the utilization of modified zeolite X or Y, specifically by incorporating boron or phosphorus ions through ion exchange. Hong et al [17,18] incorporated the ammonia pool effect in Cs-modified X zeolites and Cs-modified X zeolites with the assistance of basic picoline as a co-catalyst, effectively neutralizing the excessively strong basic center and enhancing the yield of styrene. Our early research has yielded comparable outcomes [19,20].…”