Assembly line synthesis of isoprene from formaldehyde and isobutene over SiO₂-supported MoP catalysts with active deposited carbon

Abstract

Isoprene was synthesized over MoP catalysts with active carbonaceous deposits in an “assembly line” process.

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

“…The catalyst was synthesized according to our previous work using SiO 2 as the support . Prior to use, SiO 2 having a specific surface area of 243 m 2 /g (60–100 meshes, Sinopharm Chemical Reagent Co., Ltd., China) was first calcined at 450 °C for 5 h and then dried at 110 °C in an oven.…”

“…The catalyst was synthesized according to our previous work using SiO 2 as the support. 30 Prior to use, SiO 2 having a specific surface area of 243 m 2 /g (60−100 meshes, Sinopharm Chemical Reagent Co., Ltd., China) was first calcined at 450 °C for 5 h and then dried at 110 °C in an oven. Then, 0.10 mol H 3 PO 4 and 0.01 mol (NH 4 ) 6 Mo 7 O 24 •4H 2 O was supported on 15.00 g of SiO 2 through initial wetness impregnation followed by being dried and calcined at 550 °C under air flow and then denoted as MoP.…”

“…As claimed by its catalytic applications, Ivanova et al proposed that the unsaturated hydrocarbons of carbon deposition could be protonated at the acidic sites to produce C + , which acted as “working sites” for isoprene formation. 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.…”

“…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. 30,31 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.…”

Synthesis of 1,3-Butadiene and Its 2-Substituted Monomers for Synthetic Rubbers

“…Most importantly, Ivanova et al clarified that unsaturated branched carbonaceous species in carbon deposits can generate active sites for the condensation of formaldehyde with isobutene to produce isoprene [85]. To further identify the effect of carbon deposition on the synthesis of isoprene, our group conducted the reaction over MoO 3 -P 2 O 5 [86]. 4,4-Dimethyldioxane-1,3 (DMD) has been demonstrated to be an important intermediate which can readily form on acid sites over a catalyst and further be converted into isoprene in the presence of carbonaceous species.…”