Influence of Al Oxides on Cs-SiO₂ Catalysts for Vapor Phase Aldol Condensation of Methyl Acetate and Formaldehyde

Abstract

A novel Al-promoted Cs-SiO 2 catalyst was synthesized via impregnation methods and applied in the aldol condensation reaction of methyl acetate (Ma) with formaldehyde (FA) to synthesize methyl acrylate (MA). Promotion effects of Al oxides on Cs-SiO 2 catalysts were systematically investigated. The physical−chemical properties of synthesized catalysts were characterized through XRD, FT-IR, EDS mapping, N 2 physical adsorption, NH 3 -/CO 2 -TPD, Py-IR, XPS, solid-state MAS NMR, and TG. Subsequently, the catalytic performance of fabricated catalysts was evaluated in a fixed-bed microreactor. Reaction parameters, Cs 2 O and Al 2 O 3 contents, as well as calcination temperature were optimized. The evaluation of catalytic stability was conducted under optimal reaction conditions. As a result, the introduction of Al species into Cs-SiO 2 endowed the Al−Cs−SiO 2 catalyst with superior catalytic performance and good reusability.

Leveraging the Proximity and Distribution of Cu−Cs Sites for Direct Conversion of Methanol to Esters/Aldehydes

“…[27,28] For the production of MMA based on aldol condensation, the traditional process mainly involves four steps as show in Figure 1b, including paraformaldehyde (PFA) depolymerization or oxidative dehydrogenation of MeOH to formaldehyde (FY), aldol condensation of MAc and FY to methyl acrylate (MA), MA hydrogenation to methyl propionate (MP), and aldol condensation of MP and FY to MMA, which has aroused wide research interests in previous studies. [29][30][31][32][33][34][35] Interestingly, based on the molecular formula of MMA, it is postulated to be synthesized by the condensation of methyl acetate (MAc) and 2 molar equivalents of formaldehyde (FY), in which FY can be obtained from the dehydrogenation of methanol. Hence, the overall reaction can be designed as:…”

Gradient Concentration Control of Active Components on the Industrial Cs-P/γ-Al2O3 Catalyst

“…It was clearly better than some reported catalysts; for example, the activity of the Zr-Mg-Cs/SiO 2 catalyst decreased by nearly 50% after only 32 h. In addition, the catalytic activity of the 10Cs-5P/γ-Al 2 O 3 -40 min catalyst was always higher than that of the 10Cs-5P/γ-Al 2 O 3 - i catalyst. In general, the formation of carbonaceous deposits is considered to be the main cause of catalyst deactivation. , The TG curves of spent catalysts are displayed in Figure b. Two weight loss peaks appeared in the curves at different temperature intervals.…”

“…In general, the formation of carbonaceous deposits is considered to be the main cause of catalyst deactivation. 38,39 The TG curves of spent catalysts are displayed in Figure 7b. Two weight loss peaks appeared in the curves at different temperature intervals.…”

Catalytic Cracking of Polylactic Acid to Acrylic Acid

“…In addition, acrylic acid is an important bulk chemical widely used in the manufacture of polymeric products [ 36‐37 ] and is currently produced in the petrochemical industry via two‐step gas‐phase oxidation of propylene [ 38‐40 ] or the coal chemical industry via the condensation between acetate and formaldehyde. [ 41‐43 ] The depletion of fossil resources motivates developments in the production of acrylic acid from renewable materials. [ 22‐23 ] Compared with synthesizing or recycling lactic acid or lactide from biomass or PLA, the direct cracking of PLA into acrylic acid shows great advantages in atom economy and cyclic utilization of resources.…”