Formaldehyde–isobutene Prins condensation over MFI-type zeolites

Abstract

H-ZSM-5 was identified as the most efficient catalyst for the liquid phase Prins condensation of formaldehyde with isobutene to 3-methyl-3-buten-1-ol and subsequently isoprene.

Deactivation of Zeolite Catalysts in the Prins Reaction between Propene and Formaldehyde in the Liquid Phase

“…The zeolite samples were characterized by TPD-NH 3 and nitrogen physisorption methods to estimate how acidic and textural properties influence activity and selectivity. According to obtained data, the acidity influences catalyst activity, while textural properties control product distribution, which is in agreement with previous reports [13,14,23].…”

“…Acid properties also make a great contribution to catalyst performance; the most active samples (H-BEA and H-FAU) had fewer acid sites numbers and had a broad product distribution, while H-MFI and H-MOR were more selective toward 3-buten-1-ol and had a poor conversion of formaldehyde. According to the results and previous reports [13,14,23], we assumed that samples with a higher total acid are less active due to faster deactivation of the sites by coke.…”

“…Figure 1 demonstrate the reaction network for the propene-formaldehyde Prins condensation. According to [8,13,14,23], the primary product of the olefin-formaldehyde condensation is γ-unsaturated alcohol, which undergoes further transformations. The main reaction route here is dehydration, which leads to diene hydrocarbon and a condensation with formaldehyde to form 1.3-dioxanes.…”

“…However, current industrial realizations of Prins reaction have some serious ecological drawbacks because of its use of H 2 SO 4 and H 3 PO 4 as a catalyst. In recent years, it has been shown that heterogeneous acidic materials, especially zeolites, can be used as catalysts in the Prins reaction for the production of dienes and unsaturated alcohols [8][9][10][11][12][13].…”

Depositing Different Carbon Species on MoP to Enhance Its Activity for Isoprene Production in Different Ways

“…Our previous work, based on confirming the existence of 4,4-dimethyl-1,3-dioxane (DMD) during the reaction, revealed a synergy effect between acid catalyst and carbon deposition (typically, olefinic hydrocarbons) on the isoprene synthesis. , However, carbon deposition mainly consisted of aromatic hydrocarbons and contained slight olefinic hydrocarbons. On the other hand, DMD is one of intermediates during this reaction, and it has been reported that the condensation of formaldehyde with isobutene leads to 3-methylbuten-1-ol (3MB1ol), which would be further converted to isoprene. ,,, Therefore, it still remains a great challenge to clarify the effect of carbon deposition on isoprene synthesis. Moreover, the complex composition of this carbon material leads to an improbability of controllably enhancing the activity in present conditions.…”