Enzyme-catalyzed degradation of aliphatic polycarbonates prepared from epoxides and carbon dioxide

Synthesis and characterization of biodegradable poly(butylene succinate- co-butylene fumarate)s

Ru-WOX-doped biochar for selective ethylene glycol production from cellulose hydrogenolysis: Unravelling the role of WOX in adjusting acid-metal balance

Statistical-based study using response surface methodology (RSM) was conducted to study the effects of process parameters towards biomass hydrogenation. Using Malaysian oil palm empty fruit bunches (EFB) fibres as feedstock, the central composite design (CCD) technique was employed and 18 runs were generated by CCD when four parameters (mass ratio of binary catalyst, hydrogen pressure, temperature and mass ratio of catalyst to feedstock) were varied with two center points to determine the effects of process parameters and eventually to get optimum ethylene glycol (EG) yield. RSM with quadratic function was generated for biomass hydrogenation, indicating all factors except temperature, were important in determining EG yield. Analysis of variance (ANOVA) showed a high coefficient of determination (R2) value of >0.98, ensuring a satisfactory prediction of the quadratic model with experimental data. The quadratic model suggested the optimum EG yield should be >25 wt.% and the EG yield results were successfully reproduced in the laboratory.

Techno-economic and environmental evaluation of aldehyde-assisted chemical looping separation technology in coal-based and biomass-based ethylene glycol purification

Nickel-tungsten co-doped biochar catalyst boosting ethylene glycol production from cellulose hydrogenolysis

The cathodic and anodic behavior of iron was investigated in different acetic acid/sodium acetate and borate buffer solutions. Passive oxide films were formed in pH 8.4 borate buffer solution and cathodically reduced in pH 7.0 and pH 8.4 borate as well as different acetate buffer solutions. The ratio of the two cathodic reduction arrest charges, i.e., , is related to the composition of the oxide film and tends to the almost independent of passivation potential for films reduced in borate buffer. A different ratio is, however, observed for cathodic reduction of the air‐formed oxide film on electropolished iron. For cathodic reduction in acetate buffer solutions, the ratio is quite different from that observed in borate buffer solution and depends on the concentration of the electrolyte species and the solution pH. Complex, different cathodic reduction profiles are observed in acetate buffer solutions with high electrolyte concentration and/or low pH. The results are discussed in terms of the influence of the various solution parameters on the efficiency and mechanism of oxide reduction. Passive oxide films were also formed in acetate buffer solution and were cathodically reduced in either borate or acetate buffer solution. Both the oxide film growth efficiency and composition were dependent on the nature of the acetate formation solution. In fact, a correlation exists between oxide film composition, as defined by the ratio, and anodic growth efficiency.

Poly(butylene succinate) copolyesters with terephthalic acid (T) were melt-spun into monofilaments, subsequently were drawn with draw ratio of 2-6 times. The structure and properties of these drawn fibers were examined by wide angle X-ray scattering, differential scanning calorimetry, tensile test and scanning electron microscope (SEM). The enzymatic degradation of these fibers was performed in a buffer solution with Rhizopus delemar lipase at 37°C and evaluated by weight loss, SEM observation and tensile strength retention. The copolyester with 17 mol % of T component (T-17) fiber drawn with draw ratio of 6 times at 40°C showed the much higher degradation rate than poly(butylene succinate) and the copolyester with 52 mol % of T component (T-52) fibers. Tensile strength of T-17 fiber was decreased appreciably at the initial stage of the enzymatic degradation. The degradation rate of T-17 fiber was remarkably decreased with increasing the draw ratio of the fibers due to the increase in crystallinity and the development of orientation in the amorphous region.

Hydrolysis of poly(ethylene terephthalate) and poly(ethylene 2,6-naphthalene dicarboxylate) using water at high temperature: Effect of proton on low ethylene glycol yield

BACKGROUNDThe production of value‐added chemicals from pyrolysis oil or its fractions is of great significance for the valorization of biomass. Diols, including ethylene glycol (EG) and 1,2‐propylene glycol (1,2‐PG), are important bulk chemicals with widespread industrial applications. Here we investigated the production of diols from pyrolysis oil water‐soluble fraction (WS) using a hybrid catalyst (Ni + H2WO4).RESULTSFirstly, levoglucosan, glycolaldehyde and acetol, three main components in WS, were respectively selected as the single model compound, and their respective conversions into diols were investigated at different temperatures for different reaction times. The result showed the optimum reaction temperature and time were 180 °C and 2 h respectively, under which a EG yield of 53.8% and 1,2‐PG yield of 5.2% were obtained from levoglucosan conversion, a EG yield of 98.6% was obtained from glycolaldehyde conversion, and a 1,2‐PG yield of 98.5% was obtained from acetol conversion. The reaction pathway of levoglucosan conversion was analyzed. Secondly, the model mixture of levoglucosan, glycolaldehyde and acetol was used to simulate the real WS, and their conversion was investigated at different ratios of H2WO4 to Ni. The result showed the optimum catalyst composition was 0.15 g H2WO4 and 0.3 g Ni, under which a EG yield of 76.4% and 1,2‐PG yield of 38.4% were obtained. Thirdly, the real original WS was converted under the optimum reaction conditions and the result only gave a EG yield of 19.1% and 1,2‐PG yield of 25.8% (based on the carbon moles of main substrates), which were much less than the two yields of model mixture. That was related to the presences of other types of chemicals in original WS. After the original WS being adsorbed by activated carbon, the yields of EG and 1,2‐PG could be increased to 39.2% and 37.9%, respectively.CONCLUSIONThe presences of certain other types of chemicals (such as acids, furans, phenolics and cyclopentanones) in original WS inhibited the production of diols. The activated carbon adsorption could efficiently remove most of furans, phenolics and cyclopentanones in original WS and increased significantly the diols yields. © 2024 Society of Chemical Industry (SCI).

Two series of aliphatic polyesters based on succinic acid were synthesized by copolymerization with adipic acid for the first series of saturated polyesters, and with fumaric acid for the second series. Polyesters were prepared starting from the corresponding dimethyl esters and 1,4-butanediol by melt transesterification in the presence of a highly effective catalyst tetra-n-butyl-titanate, Ti(0Bu)4. The molecular structure and composition of the copolyesters was determined by 1H NMR spectroscopy. The effect of copolymer composition on the physical and thermal properties of these random polyesters were investigated using differential scanning calorimetry. The degree of crystallinity was determined by DSC and wide angle X-ray. The degrees of crystallinity of the saturated and unsaturated copolyesters were generally reduced with respect to poly(butylene succinate), PBS. The melting temperatures of the saturated polyesters were lower, while the melting temperatures of the unsaturated copolyesters were higher than the melting temperature of PBS. The biodegradability of the polyesters was investigated by enzymatic degradation tests. The enzymatic degradation tests were performed in a buffer solution with Candida cylindracea lipase and for the unsaturated polyesters with Rhizopus arrhizus lipase. The extent of biodegradation was quantified as the weight loss of polyester films. Also the surface of the polyester films after degradation was observed using optical microscopy. It could be concluded that the biodegradability depended strongly on the degree of crystallinity, but also on the flexibility of the chain backbone. The highest biodegradation was observed for copolyesters containing 50 mol.% of adipic acid units, and in the series of unsaturated polyesters for copolyesters containing 5 and 10 mol.% of fumarate units. Although the degree of crystallinity of the unsaturated polyesters decreased slightly with increasing unsaturation, the biodegradation was not enhanced suggesting that not only the chemical structure and molecular stiffness but also the morphology of the spherulites influenced the biodegradation properties.

Catalytic conversion of cellulosic biomass to ethylene glycol: Effects of inorganic impurities in biomass

Catalytic conversion of glucose and cellobiose into ethylene glycol over various tungsten-based catalysts

Enhanced yield of ethylene glycol production from d-xylose by pathway optimization in Escherichia coli.

Biodegradable aliphatic polyesters. Part I. Properties and biodegradation of poly(butylene succinate- co-butylene adipate)

A-C1 protein is the product of a tumor suppressor gene negatively regulating the oncogene Ras and belongs to the HRASLS (HRAS-like suppressor) subfamily. We recently found that four members of this subfamily expressed in human tissues function as phospholipid-metabolizing enzymes. Here we examined a possible enzyme activity of A-C1. The homogenates of COS-7 cells overexpressing recombinant A-C1s from human, mouse, and rat showed a phospholipase A½ (PLA½) activity toward phosphatidylcholine (PC). This finding was confirmed with the purified A-C1. The activity was Ca²⁺ independent, and dithiothreitol and Nonidet P-40 were indispensable for full activity. Phosphatidylethanolamine (PE) was also a substrate and the phospholipase A₁ (PLA₁) activity was dominant over the PLA₂ activity. Furthermore, the protein exhibited acyltransferase activities transferring an acyl group of PCs to the amino group of PEs and the hydroxyl group of lyso PCs. As for tissue distribution in human, mouse, and rat, A-C1 mRNA was abundantly expressed in testis, skeletal muscle, brain, and heart. These results demonstrate that A-C1 is a novel phospholipid-metabolizing enzyme. Moreover, the fact that all five members of the HRASLS subfamily, including A-C1, show similar catalytic properties strongly suggests that these proteins constitute a new class of enzymes showing PLA½ and acyltransferase activities.