Excess soluble alkalis to prepare highly efficient MgO with relative low surface oxygen content applied in DMC synthesis

Abstract

The activities of various MgO catalysts, which were prepared from different methods such as hydration synthesis, thermal decomposition, combustion, sol–gel and co-precipitation, were conducted in dimethyl carbonate (DMC) synthesis via transesterification of ethylene carbonate with methanol. MgO-P-Na2CO3-3.14 synthesized by the excess Na2CO3 precipitation compared the best catalytic activity and stability, which could be reused for seven times without obvious deactivation. The DMC yield was as high as 69.97% at 68 °C. The transesterification reaction could be separated into two steps, and the samples obtained by NaOH precipitant exhibited better ring-opening capability, while the catalysts acquired by Na2CO3 precipitant displayed superior transesterification ability. The structure-performance relationship was evaluated by multiple characterization methods. The results indicated that the as-synthesized catalyst derived from dried precursors with more crystalline magnesium carbonate was favorable for the promotion of DMC yield, and MgO-P-Na2CO3-3.14 with more Mg-O pairs, which were the active center for the transesterification of 2-hydroxyethyl methyl carbonate (HEMC) intermediate with methanol, resulted in more moderately basic sites left that was in accordance with the DMC yield variation. MgO-P-Na2CO3-3.14 with greater BET surface area and mesopore volume, relative low surface oxygen content and larger moderately basic sites amount compared the excellent activity in DMC synthesis.

An Efficient and Super Stable Immobilized Ionic Liquid Catalyst Application in the Catalytic Synthesis of Carbonates

“…The products were analyzed by a GC-2010 plus gas chromatography. The EC conversion, DMC selectivity, and DMC yield refer to the previous work …”

“…Based on the research in previous work, 22 the mechanism of EC transesterification with a MeOH catalyst by PS-IMC4IM was proposed, and the results are shown in Figure 8. The imidazole anion in PS-IMC4IM can activate methanol to methoxy anion, which has nucleophilicity and can attack the carbonyl carbon on EC to transform into ionic intermediates, and the intermediates react with H + in imidazole to form the hydroxyethyl methyl carbonate (HEMC).…”

“…The EC conversion, DMC selectivity, and DMC yield refer to the previous work. 22 The turnover frequency (TOF) was calculated by the following formula 1:…”

Morphology Design and Fabrication of Bio-Inspired Nano-MgO–Mg(OH)2 via Vapor Steaming to Enable Bulk CO2 Diffusion and Capture

“…The O 1s spectra showed that the peaks related to -OH were derived from the chemisorbed -OH groups on the surface of MgO during steaming with binding energy values of 531.89 eV, 532.03 eV, and 531.89 eV for 10-min, 15-min, and 20-min steam exposed samples. It was seen that the peak intensities in the Mg 2p spectra increased with increased steaming time, indicating the improved formation of Mg(OH)2 due to the chemisorption of -OH in MgO [28].…”

Magnesium Oxide (MgO) as a Sustainable Catalyst for Biodiesel Production from Waste Cooking Oil: A Comparative Study with KOH

“…MgO exhibits excellent catalytic activity due to its high surface area and inherent basicity, which are crucial for facilitating the transesterification reaction [11]. The stability of MgO under the reaction conditions is noteworthy, as it maintains its structural integrity and catalytic performance, making it a strong choice both for continuous and batch processes [12][13][14]. Mg-doped CaO-MgO catalysts prepared by co-precipitation showed improved activity and stability in transesterification for biodiesel production.…”