Higher Alcohol Yield Research Articles

Reaction of ethanol over hydroxyapatite affected by Ca/P ratio of catalyst

The mineral hydroxyapatite [HAP; Ca 10(PO 4) 6(OH) 2] is the chief component of animal bones and teeth. It also is known to function as a catalyst with both acid and base sites, depending on the manner in which it is synthesized. We closely studied the reaction of ethanol over HAP using catalysts of different Ca/P molar ratios. These were prepared by controlling the pH of the solution during precipitation synthesis. We found that the distribution of acid sites and basic sites on the catalyst surface varied with the Ca/P ratio of HAP. The yields of ethylene, 1-butanol, and 1,3-butadiene were correlated with the ratio of acid sites and basic sites. We further found that yields of higher alcohols, such as 1-butanol, that are known as Guerbet alcohols and are characteristic products of ethanol over HAP, are functions of the probability of ethanol activation ( α) on the catalyst surface.

An emergent catalytic material: Pt/ZnO catalyst for selective hydrogenation of crotonaldehyde

By using modifiers in platinum catalysts it is possible to modulate the hydrogenation selectivity in α, β-unsaturated aldehydes carbonyl bond with regard to olefinic bond hydrogenation. The challenge is to find an emergent catalytic material able to produce 100% unsaturated alcohol. In this field, 1% Pt/ZnO catalysts were tested in hydrogenation of crotonaldehyde, in gas phase, at atmospheric pressure. The catalysts were prepared by impregnation of ZnO from two different precursors, H 2PtCl 6 and Pt(NH 3) 4(NO 3) 2, followed by calcination at 673 K and tested after reduction at different temperatures, 473–773 K. The ex-nitrate and ex-chloride catalysts showed quite different catalytic behaviors. The ex-chloride was much more active and selective; in certain conditions 90% crotyl alcohol selectivity was reached. Different techniques (TPR, XRD, TEM, XPS, FTIR) were used to characterize both types of catalysts and to correlate the structure and the reactivity. The Lewis acidity of ZnO after the reduction treatment and the formation of PtZn alloy were found to be the key factors leading to high crotyl alcohol yield. It was proposed that modification of the electronic properties of platinum both by alloying to zinc and by Lewis acidity of the support reinforced by chlorine changes the adsorption mode of crotonaldehyde by favoring the binding of the terminal oxygen of the molecule to the electronically modified platinum atom.

A highly active K-Co-Mo/C catalyst for mixed alcohol synthesis from CO + H2.

A highly homogeneous and dispersed K-Co-Mo/C catalyst which prepared by a sol-gel method exhibits high alcohol yield, especially high C2+ OH selectivity for mixed alcohol synthesis from CO + H2.

Starch hydrolysis and its effect on product yield and microbial contamination in yeast ethanol fermentation

The influence of temperature and incubation time on starch gelatinization in wheat, rye and corn grain were studied. Rye starch was the most susceptlble to enzyme hydrolysls. Heat treatment of ground grain during starch gelatinlzation significantly reduced microblal contamination. In the batch fermentation of wheat, a high sugar utillization ranged from 92 to 94%. The highest alcohol yield was 65% from rye starch. The results obtained show that the high pressure cooking used for mash preparation can be replaced successfully by low temperature treatment.

ChemInform Abstract: Direct Alcohol Synthesis Using Copper/Cobalt Catalysts

The authors have measured the yields of methanol, higher alcohols, and hydrocarbons during CO hydrogenation on a Cu/Co/ZnO/Al{sub 2}O{sub 3}/K catalyst. The overall yield of higher alcohols increases linearly with CO conversion, and the individual higher alcohol yields obey a Schulz-Flory distribution through n-C{sub 6}H{sub 13}OH. The selectivity for hydrocarbon products also increases with CO conversion. The product alcohols do not undergo a significant degree of secondary reaction at the concentrations formed under these conditions. The overall results are consistent with a mechanism for higher alcohol synthesis that involves chain growth of a common surface alkyl intermediate, followed by a chain termination step which determines whether the final product desorbs as an alcohol or hydrocarbon. The selectivity of the termination step shifts toward greater hydrocarbon formation with increasing CO conversion. 20 refs.

Extrusion cooking of grains for ethanol production

Ethanol produced by fermentation was used in the past and is still used as an extender or replacer of fossil fuel. Extrusion cooking of cereal grains or starches is a flexible processing method which is capable of producing precooked starches and flours having a wide variety of functional properties. Rheological properties of starch are emphasised in this paper. Extrusion-cooked substrates for fermentation into alcohol produce a high alcohol yield, and have a short conversion time. The extrusion cooking of cereals has low energy requirements.

Malt Pasteurization, Sterilization of Barley Malt with Gamma Radiation

Off-flavored distillates are occasionally produced during the processing of grain mashes to beverage alcohol which can be traced to metabolic activities of bacteria that survive the saccharification step in mashing in which the mesh is maintained at 145 deg F for a short time. Barley malt is the principal source of these bacteria, which are mainly lactobacilli; therefore, attempts were made to sterilize the malt by Co/sup 60/ gamma irradintion. It was shown that 0.112- Mrad irradiation reduced the bacterial counts of malts to very low levels whereas no significant reduction in alpha -amylase or alcohol yields occurred. Higher dosages of radiation resulted in substantially complete sterilizntion of the malts but also in some destruction of their amylase activities. Pre-irradiation of malt caused progressively lower maximum bacterial populations and lengthened lag phases as more radiation was used; however, the rate of multiplication in the exponential growth phases was not influenced by the amount of radiation. Heating subsequent to irradiation has been shown to have a synergistic lethal effect on bacteria, but no significant difference between irradiated and nonirradiated malts or of saccharificntion temperature upon alcohol yields was found. In some trials, higher alcohol yields were obtained from irradiated malts usedmore » at a saccharification temperature of 125 deg F, suggesting that some destruction of malt amylase occurs by saccharifying at 145 deg F. Results using malts treated with gamma and cathode rays are compared. A 1% reduction of alcohol yield was caused by 0.4 Mrad of cathode rays and by 1.1 Mrad of gamma rays. Beyond the amount of radiation causing 1% reduction, the yields drop rapidly with either kind of radiation. The alpha -amylase content of malt is not significantly reduced by irradiation with less than 0.04 Mrad of either gamma or cathode rays, Beyond 0.04 Mrad, however, the alpha -amylase content decreases rapidly with both kinds of radiations, no significant difference being apparent between the action of gamma and cathode rays on this enzyme. It is estimated that the cost of pasteurization of grain using 0.1 Mrad Co/sup 60/ irradiation would be approximately ton. (BBB)« less