Oxidized Biochar as a Simple, Renewable Catalyst for the Production of Cyclic Carbonates from Carbon Dioxide and Epoxides

Abstract

Hard‐ and softwood residues (from birch and pine respectively) of forestry, pulp, and paper industries (e. g. sawdust, branches) were used to prepare biochar, which was then oxidized using nitric acid to produce catalytic carboxylic acid functionalized biochar. This oxidized biochar, ox–bc, in the presence of a co‐catalyst, showed excellent catalytic activity towards the cycloaddition reaction between CO2 and epoxides using mild conditions (CO2 pressure, 10 bar). No differences in catalytic activity were seen between the two types of oxidized biochar despite the hardwood ox–bc having a significantly higher surface area. The catalysts function through activation of the epoxide reagent via hydrogen‐bonding with carboxylic acid groups on the surface. The number of surface acid groups was reduced by reaction with 3‐aminopropyltriethoxysilane and the resulting material was inactive in the reactions studied. The ox–bc catalysts are sustainable, economic, and renewable alternatives for currently used heterogeneous systems and are also the first carbon‐based materials derived from biomass to exhibit good recyclability (over five runs) with a broad substrate scope for the production of cyclic carbonates from epoxides and CO2.

Synthesis of Bio‐Based Cyclic Carbonates Using a Bio‐Based Hydrogen Bond Donor: Application of Ascorbic Acid to the Cycloaddition of CO2 to Oleochemicals

“…In the cycloaddition of CO 2 to epoxides, HBDs are able to activate and coordinate the epoxide substrate and the intermediates of reaction by establishing arrays of H‐bonds . The application of HBDs, in particular those represented by naturally available small molecules (i. e. vitamins, amino acids and peptides, sugars, and derivatives), or produced from agricultural residues, is clearly advantageous over metalorganic Lewis acids. This is particularly the case, when the synthesis of the latter involves multistep preparation of oil‐based organic ligands, use of expensive and highly air sensitive organometallic precursors or potentially “endangered” or rare metal centers .…”

A Review of Non-Soil Biochar Applications

“…Vidal et al [335] developed an amino-siloxy-oxidized biochar that was able to promote the conversion of epoxy compounds and CO 2 into glycerol carbonate.…”

Metal and Co‐Catalyst Free CO2 Conversion with a Bifunctional Covalent Organic Framework (COF)

“…[6,7] Compared with the straightforward CCS, chemical transformation of CO 2 has attracted the surge of attention, because it could not only control the excessive growth of CO 2 but also achieve the cyclic utilization of carbon. [8,9] The coupling of CO 2 with epoxides, is one of the most common approaches for preparing cyclic carbonates that hve been extensively applied in a variety of chemical feedstocks. Nevertheless, the CO 2 conversion usually requires strict reaction conditions due to the thermodynamically stable and inert nature of CO 2 .…”