On the Effect of the M3+ Origin on the Properties and Aldol Condensation Performance of MgM3+ Hydrotalcites and Mixed Oxides

Hydrotalcites (HTCs) are promising solid base catalysts to produce advanced biofuels by aldol condensation. Their main potential lies in the tunability of their acid-base properties by varying their composition. However, the relationship between the composition of hydrotalcites, their basicity, and their catalytic performance has not yet been fully revealed. Here, we investigate systematically the preparation of HTCs with the general formula of Mg6M3+2(OH)16CO3·4H2O, where M3+ stands for Al, Ga, Fe, and In, while keeping the Mg/M3+ equal to 3. We use an array of analytical methods including XRD, N2 physisorption, CO2-TPD, TGA-MS, FTIR-ATR, and SEM to assess changes in the properties and concluded that the nature of M3+ affected the HTC crystallinity. We show that the basicity of the HTC-derived mixed oxides decreased with the increase in atomic weight of M3+, which was reflected by decreased furfural conversion in its aldol condensation with acetone. We demonstrate that all MgM3+ mixed oxides can be fully rehydrated, which boosted their activity in aldol condensation. Taking all characterization results together, we conclude that the catalytic performance of the rehydrated HTCs is determined by the “host” MgO component, rather than the nature of M3+.

Structured hydroxyapatite composites as efficient solid base catalysts for condensation reactions

Herein, we report the use of structured hydroxyapatite composite (SHCs) as highly efficient and recyclable solid base catalysts for various condensation reactions.

Sustainable Synthesis of Vinyl Methyl Ether from Biomass-derived Ethylene Glycol Dimethyl Ether over Solid Base Catalysts

Vinyl methyl ether (VME) is an important chemical intermediate for the production of functional polymers and fine chemicals. It is primarily produced in industry via the addition of methanol to...

Design of nitrogen-doped graphitized 2D hierarchical porous carbons as efficient solid base catalysts for transesterification to biodiesel

2D graphitized porous carbons decorated with high contents of nitrogen sites such as pyridinic nitrogen were developed, which were used as efficient and reusable solid base catalysts for transesterification to biodiesel.

Effect of Solid Bases Catalyst on Conversion of Acrylonitrile into Acrylic Acid by Hydrothermal Reaction

This study aims at the shortcomings of the current industrial application of acrylonitrile wastewater treatment, using alkali-catalyzed hydrothermal technology to convert acrylonitrile into acrylic acid for achieving resource utilization. In this study, alkali metal, alkaline earth metal hydroxide and composite solid base were used as catalysts to investigate catalytic effects of these solid based on the hydrothermal reaction. The results show when using the alkali and alkaline-earth metal hydroxides as catalysts, the best effect of treatment was KOH and the highest yield of acrylic acid reached 56.60%. It was also found that, among the three kinds of solid base catalysts (Ca-O-Mg, K-O-Al, K-O-Si) adopted with the same mass and various loading capacity, K-O-Si (15%) was the most effective catalyst for the conversion of acrylonitrile, and the highest yield of acrylic acid reached 57.78%. This process provides an environmentally friendly method toward the synthesis of useful acrylic acid from acrylonitrile within a very short time.

Core–shell magnetic mesoporous N-doped silica nanoparticles: solid base catalysts for the preparation of some arylpyrimido[4,5-b]quinoline diones under green conditions

Preparation of core–shell magnetic mesoporous N-doped silica nanoparticles as a new solid base catalyst was studied. obtained catalyst was used for the preparation of some arylpyrimido[4,5-b]quinoline diones under green conditions.