Greenness Assessment and Synthesis for the Bio-Based Production of the Solvent 2,2,5,5-Tetramethyloxolane (TMO)

2,2,5,5-tetramethyloxolane (TMO) has recently been identified and demonstrated as a safer solvent to replace toluene, THF, and hydrocarbons in a handful of applications. Herein, several bio-based routes to TMO are presented and assessed for greenness, assisted by the CHEM21 Metrics Toolkit and BioLogicTool plots. Using glucose as a common starting point, two chemocatalytic routes and two biochemical routes to TMO were identified and the pathways compared using the aforementioned tools. In addition, bio-based TMO was synthesised via one of these routes; from methyl levulinate supplied by Avantium, a by-product of the sugar dehydration step during the production of 2,5-furandicarboxylic acid. First, methyl levulinate underwent triple methylation using methyl magnesium chloride (MeMgCl) to yield 2,5-dimethylhexane-2,5-diol (DHL) in high yields of 89.7%. Then DHL was converted to high purity TMO (>98.5%) by cyclodehydration using H-BEA zeolites based on the previously reported approach. Bio-based content of this TMO was confirmed by ASTM D6866-20 Method B and found to have 64% bio-based carbon, well above the threshold of 25% set by CEN/TC 411 standards and matching the anticipated content. This study represents the first demonstration of a bio-based synthesis of TMO and confirmation of bio-content by accepted standards.

Physical-Chemical Properties and Engine Performance of Blends of Biofuels with Gasoline

Addition of 10 vol% biomass-based methyl levulinate (ML), ethyl levulinate (EL), butyl levulinate (BL), gamma-valerolactone (GVL), dimethyl carbonate (DimC), and diethyl carbonate (DieC) in gasoline were selected as blended fuels. Physical-chemical properties of six different blends of biofuels and gasoline, including miscibility, octane number, distillation, vapor pressure, unwashed gum content, solvent washed gum content, copper corrosiveness, water content, mechanical admixtures, and lower heating value was evaluated according to the China National Standards. Blended fuels were then evaluated on the performance and emissions of a gasoline test engine without any modification. The results showed that all biomass-based fuels at 10 vol% have good miscibility in gasoline at temperatures of –30 to 30 °C. Experiments were performed at 4500 rpm engine speed at different engine loads (from 10% to 100% in 10% intervals). Results showed slightly lower engine power at different loads with the blended fuels than those from gasoline fuelled engine. However, the brake specific fuel consumption (BSFC) with the blended fuels was slightly higher than that from gasoline. Emission of carbon monoxide (CO), total unburned hydrocarbon (THC) and oxides of nitrogen (NOx) was reduced significantly from the blended fuels compared to gasoline while carbon dioxide (CO2) emission was slightly higher than that from gasoline. The data suggests that 10 vol% addition of biomass-based levulinates and carbonates fuels to gasoline is suitable for use in gasoline engines.