Presence Of Various Acid Catalysts Research Articles

Influence of acid catalyst on two step transesterification of Karanja oil with high free fatty acids

Karanja oil methyl ester (KOME) was produced by the two step transesterification of oil with an alcohol in the presence of various acid catalysts and base catalysts. The best result was obtained with H2SO4 as acid catalyst and KOH as base catalyst; the yield was 97% at 60°C after 150 min. The high yield was observed due to the reduction of free fatty acids (FFA) % by using an acid catalyst in the first step of transesterification. HCl and H3PO4 was less active than H2SO4 during the process as it presented very low ester yields for the various molar ratios of fatty acid to alcohol studied. The fatty acid profile of the oil (palmitic acid: 11.64%; stearic acid: 7.70%; docosanoic acid: 4.46%; tetracosanoic acid: 1.08%; linolenic acid: 16.66%; oleic acid: 51.61%; eicosanoic acid: 1.33) and the different reactive actions of the acids were responsible for the observed differences in conversion to methyl esters. The result attained by this study might contribute to the economic utilization of a nonedible feedstock.

Effect of Liquefying Agents Mixed with Lower Alcohols and Catalyst on the Microwave Driven Liquefaction of Wood

Southern pine (Pinus sp.) is liquefied by microwave heating and PEG/lower alcohols mixtures in the presence of various acid catalysts at 150 °C. The reaction time is of 15 min, and the liquefaction solvent to wood ratio is of 2:1. The mixing of lower alcohols such as ethanol with PEG had a strong effect on the liquefaction process, especially for the liquefaction ratio. The catalyst, phosphoric acid, could improve the liquefaction yield and the value of hydroxyl in the biomass liquefaction process. Consequently, the use of PEG/ethanol mixtures and a catalyst of phosphoric acid was benefit to improve liquefaction efficiency and utilization of liquefied products.

Alkoxylation and hydration of camphene in the presence of acid catalysts

The alkoxylation of camphene in the presence of various acid catalysts is studied. Alkylisobornyl ethers are obtained in high yields if the heteropolyacidsH4SiW12O40 andH3PW12O40 are used as the catalysts. The mechanism of the acid-catalyzed hydration of camphene in aqueous-alcohol solutions is examined.

Acid catalysed steaming for solubilization of bamboo grass xylan

Culms of bamboo grass ( Sasa senanensis Rehd.) were treated with saturated steam at a range of temperatures between 170 and 197°C for 10 min in the presence of various acid catalysts in order to improve solubilization of the xylan in the substrate. The catalysts were Lewis acids, inorganic salts and organic acids. These compounds strongly modified the steam-hydrolysis and solubilization of bamboo grass xylan. The use of low levels of Lewis acids or CaCl 2 had the advantage of a substantial reduction in temperature requirement for the steaming treatment. The solubilized sugars were mainly composed of xylose, arabinose and low molecular weight xylo-oligosaccharides.

Acid Reactions of Lignin Models of β-5 Type

Summary Refluxing of trans–2-(3,4-dimethoxyphenyl)-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzo[b]furan with dioxane-water (9 : 1) in the presence of various acid catalysts led to the formation of 2-(3,4-dimethoxyphenyl)- 7-methoxy-3-methylbenzo[b]furan, the trans and cis forms of 2-hydroxy-3,3′4′-trimethoxystilbene and cis–2-(3,4-dimethoxyphenyl)-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzo[b]furan. The proportions of the products were strongly dependent on the particular acid used as catalyst. HCl and to a greater extent HBr favored the formation of the 2-arylbenzofuran (phenylcoumarone) while the trans-stilbene derivative predominated in reaction products from the experiments with trifluoromethane sulfonic acid as the catalyst. Isomerization of the starting material occurred, regardless of the nature of the catalyst (small amounts of the cis-isomer formed). The number of phenylpropane units in spruce lignin attached to an adjacent unit by a β−5 linkage was estimated to be 6–9% on the basis of 1H NMR spectrometric measurements of the formation of phenylcoumarone structures on refluxing of milled wood lignin from spruce with 0.1M HBr in dioxane-water (9 : 1).

Catalyzed steaming as pre-treatment for the enzymatic hydrolysis of bamboo grass culms

Culms of bamboo grass ( Sasa senanensis Rehd.) were treated with saturated steam at 197°C for 10 min in the presence of various acid catalysts in order to improve enzymatic susceptibility. Catalyst levels were varied at 5, 10, 20 and 30 mmol kg −1 original material. The catalysts were Lewis acids, NH 4Cl, (NH 4) 2SO 4, acetic acid and organic acid anhydrides. The extent of enzymatic hydrolysis of steamed substrate was improved by the addition of catalyst. The acid catalysts strongly modified the steam treatment of bamboo grass culms. Overall recovery of the steamed solids decreased with increase in concentration of the catalyst. Conversion yields from 60 to 70%, based on polysaccharides present in the original material, were achieved by catalyzed steaming followed by enzymatic hydrolysis.