scispace - formally typeset



About: Methanol is a(n) research topic. Over the lifetime, 38663 publication(s) have been published within this topic receiving 854883 citation(s). The topic is also known as: methyl alcohol & wood alcohol.

More filters
Book ChapterDOI
Abstract: Publisher Summary Catalase exerts a dual function: (1) decomposition of H 2 O 2 to give H 2 O and O 2 (catalytic activity) and (2) oxidation of H donors, for example, methanol, ethanol, formic acid, phenols, with the consumption of 1 mol of peroxide (peroxide activity) The kinetics of catalase does not obey the normal pattern Measurements of enzyme activity at substrate saturation or determination of the K s is therefore impossible In contrast to reactions proceeding at substrate saturation, the enzymic decomposition of H 2 O 2 is a first-order reaction, the rate of which is always proportional to the peroxide concentration present Consequently, to avoid a rapid decrease in the initial rate of the reaction, the assay must be carried out with relatively low concentrations of H 2 O 2 (about 001 M) This chapter discusses the catalytic activity of catalase The method of choice for biological material, however, is ultraviolet (UV) spectrophotometry Titrimetric methods are suitable for comparative studies For large series of measurements, there are either simple screening tests, which give a quick indication of the approximative catalase activity, or automated methods

17,516 citations

Journal ArticleDOI
Abstract: The transport properties and the swelling behaviour of NAFION and different sulfonated polyetherketones are explained in terms of distinct differences on the microstructures and in the p K a of the acidic functional groups. The less pronounced hydrophobic/hydrophilic separation of sulfonated polyetherketones compared to NAFION corresponds to narrower, less connected hydrophilic channels and to larger separations between less acidic sulfonic acid functional groups. At high water contents, this is shown to significantly reduce electroosmotic drag and water permeation whilst maintaining high proton conductivity. Blending of sulfonated polyetherketones with other polyaryls even further reduces the solvent permeation (a factor of 20 compared to NAFION), increases the membrane flexibility in the dry state and leads to an improved swelling behaviour. Therefore, polymers based on sulfonated polyetherketones are not only interesting low-cost alternative membrane material for hydrogen fuel cell applications, they may also help to reduce the problems associated with high water drag and high methanol cross-over in direct liquid methanol fuel cells (DMFC). The relatively high conductivities observed for oligomers containing imidazole as functional groups may be exploited in fully polymeric proton conducting systems with no volatile proton solvent operating at temperatures significantly beyond 100°C, where methanol vapour may be used as a fuel in DMFCs.

2,631 citations

Journal ArticleDOI
TL;DR: Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification with methanol, has attracted considerable attention during the past decade as a renewable, biodegradable, and nontoxic fuel.
Abstract: Biodiesel (fatty acid methyl esters), which is derived from triglycerides by transesterification with methanol, has attracted considerable attention during the past decade as a renewable, biodegradable, and nontoxic fuel. Several processes for biodiesel fuel production have been developed, among which transesterification using alkali-catalysis gives high levels of conversion of triglycerides to their corresponding methyl esters in short reaction times. This process has therefore been widely utilized for biodiesel fuel production in a number of countries. Recently, enzymatic transesterification using lipase has become more attractive for biodiesel fuel production, since the glycerol produced as a by-product can easily be recovered and the purification of fatty methyl esters is simple to accomplish. The main hurdle to the commercialization of this system is the cost of lipase production. As a means of reducing the cost, the use of whole cell biocatalysts immobilized within biomass support particles is significantly advantageous since immobilization can be achieved spontaneously during batch cultivation, and in addition, no purification is necessary. The lipase production cost can be further lowered using genetic engineering technology, such as by developing lipases with high levels of expression and/or stability towards methanol. Hence, whole cell biocatalysts appear to have great potential for industrial application.

2,117 citations

Journal ArticleDOI
Abstract: Biodiesel is an alternative diesel fuel that is produced from vegetable oils and animal fats. It consists of the monoalkyl esters formed by a catalyzed reaction of the triglycerides in the oil or fat with a simple monohydric alcohol. The reaction conditions generally involve a trade-off between reaction time and temperature as reaction completeness is the most critical fuel quality parameter. Much of the process complexity originates from contaminants in the feedstock, such as water and free fatty acids, or impurities in the final product, such as methanol, free glycerol, and soap. Processes have been developed to produce biodiesel from high free fatty acid feedstocks, such as recycled restaurant grease, animal fats, and soapstock.

2,044 citations

Journal ArticleDOI
Abstract: Biodiesel is a low-emissions diesel substitute fuel made from renewable resources and waste lipid. The most common way to produce biodiesel is through transesterification, especially alkali-catalyzed transesterification. When the raw materials (oils or fats) have a high percentage of free fatty acids or water, the alkali catalyst will react with the free fatty acids to form soaps. The water can hydrolyze the triglycerides into diglycerides and form more free fatty acids. Both of the above reactions are undesirable and reduce the yield of the biodiesel product. In this situation, the acidic materials should be pre-treated to inhibit the saponification reaction. This paper reviews the different approaches of reducing free fatty acids in the raw oil and refinement of crude biodiesel that are adopted in the industry. The main factors affecting the yield of biodiesel, i.e. alcohol quantity, reaction time, reaction temperature and catalyst concentration, are discussed. This paper also described other new processes of biodiesel production. For instance, the Biox co-solvent process converts triglycerides to esters through the selection of inert co-solvents that generates a one-phase oil-rich system. The non-catalytic supercritical methanol process is advantageous in terms of shorter reaction time and lesser purification steps but requires high temperature and pressure. For the in situ biodiesel process, the oilseeds are treated directly with methanol in which the catalyst has been preciously dissolved at ambient temperatures and pressure to perform the transesterification of oils in the oilseeds. This process, however, cannot handle waste cooking oils and animal fats.

1,968 citations

Network Information
Related Topics (5)
Aqueous solution

189.5K papers, 3.4M citations

91% related

400.9K papers, 8.7M citations

89% related

226.4K papers, 5.9M citations

88% related

223.5K papers, 2M citations

86% related

132.2K papers, 2.5M citations

86% related
No. of papers in the topic in previous years