Effect Of Additional Water Research Articles

Electrochemical Conversion of CO2 to Fuels and Useful Chemicals over Metal Supported Solid Oxide Electrolyzers

Electrochemical conversion of CO2 and H2O to fuels and chemicals provides a promising approach to simultaneously mitigate greenhouse emission and store surplus energy, which reduces electricity network variation due to increased intermittent renewable energy (such as solar and wind) utilization. Metal supported solid oxide electrolyzers (MS-SOEs) developed at Lawrence Berkeley National Laboratory provide advantages of rapid start-up, mechanical ruggedness, redox tolerance, dynamic operation, and low-cost materials. A relatively high operating temperature range of 600 to 750°C promotes energy efficiency and allows utilization of thermal energy such as steam.In this work, efficient and stable catalysts developed at the University of South Carolina have been infiltrated in the symmetrical and porous MS-SOE architecture. The phase purity has been analyzed by X-day diffraction. The morphologies of these infiltrated and posttest catalysts have been examined by scanning electron microscopy. Optimization of cell structure, processing temperature, cell voltage, and catalyst infiltration cycles for better cell performance will be presented. The stability of MS-SOEs has been evaluated during continuous operation for >200 hours. The cell degradation mechanisms revealed by electrochemical impedance spectroscopy and high-resolution scanning electron microscopy techniques will be presented.In addition to pure CO2 electrochemical conversion, effects of additional water and hydrogen in CO2 feedstock will be analyzed. Faradic efficiency and chemical selectivity calculated from gas chromatograph and electrochemical analyses will be presented.

Mechanistic studies on the cascade conversion of 1,3-dihydroxyacetone and formaldehyde into α-hydroxy-γ-butyrolactone.

The chemical synthesis of commercially and industrially important products from biomass-derived sugars is absolutely vital to establish biomass utilization as a sustainable alternative source of chemical starting materials. α-Hydroxy-γ-butyrolactone is a useful synthetic intermediate in pharmaceutical chemistry, and so novel biomass-related routes for its production may help to validate this eco-friendly methodology. Herein, we report the specific catalytic activity of homogeneous tin halides to convert the biomass-derived triose sugar 1,3-dihydroxyacetone and formaldehyde into α-hydroxy-γ-butyrolactone. A detailed screening of catalysts showed the suitability of tin catalysts for this reaction system, and isotope experiments using [D2]paraformaldehyde, substrate screening, and time profile measurements allowed us to propose a detailed reaction pathway. In addition, to elucidate the activated species in this cascade reaction, the effect of additional water and the influence of additional Brønsted acids on the reaction preferences for the formation of α-hydroxy-γ-butyrolactone, lactic acid, and vinyl glycolate were investigated. The active form of the Sn catalyst was investigated by (119)Sn NMR spectroscopy.

Insight into the Formation and Reactivity of Framework‐Bound Methoxide Species in H‐ZSM‐5 from Static and Dynamic Molecular Simulations

AbstractFramework‐bound methoxides occur as intermediates in the stepwise mechanism for zeolite‐catalyzed methylation reactions. Herein, the formation of methoxides from methanol or dimethyl ether in H‐ZSM‐5 is investigated by a combination of static and dynamic simulations, with particular focus on the effect of additional water and methanol molecules on the mechanism and kinetics. Metadynamics simulations allow partitioning the reaction path into distinct phases. Proton transfer from the zeolite to the reactants is found to be the rate‐limiting phase in the methoxide formation. Additional methanol molecules only assist the proton transfer in the methoxide formation from methanol, whereas the reaction from dimethyl ether does not benefit from methanol assistance. Once formed, methoxides are found to be as reactive toward alkene methylation as methanol and dimethyl ether.

Mono- and di-acylglycerol synthesis in CO 2-expanded acetone

Enzymatic esterification of glycerol and palmitic acid was performed in acetone expanded by CO 2 at 40–60 °C and 65–85 bar. Novozyme 435, Lipozyme RM IM, Lipozyme TL IM and Lipomod 34P were screened to select a suitable enzyme for the study. The effects of additional water and molar ratio of glycerol to palmitic acid on the selectivity to mono- and di-acylglycerol were investigated. Response surface method was used to describe the dependency of pressure, temperature, and enzyme concentration on the conversion of palmitic acid. Optimum condition was finally selected at 85 bar, 50 °C and 25% of Novozyme 435 related to the amount of dissolved fatty acid.

The effect of direct rainfall and runoff on microbial activities along an arid hillslope, northern Negev, Israel

We studied the influence of runoff water and moisture regime on the microbial communities in desert soil along a hillslope in the northern Negev desert (Israel) during two winter seasons. Wetting of the soil by winter rainstorms had a pronounced influence on microbiological parameters. In most cases the first significant wetting of the season generated a strong burst in activity. This occurred at different timing according to the location of the sampling site with relation to runoff input. Field data and laboratory simulation experiments suggest that the effect of additional water throughout the season depends on the response of the vegetation to moisture distribution in time.

Increasing Rangeland Forage Production by Water Harvesting

Effects of additional water, provided from adjacent water-collecting areas, on forage production of blue panicgrass (Panicum antidotule Retz.) were assessed. Applying paraffin for water repellency of runoff areas increased water for use on the collecting areas. In this 3-year study, more than 2,000 kg/ha/year forage was harvested with rainfall of less than 130 mm and collecting-area runoff from 14 summer events in 1974 and from 18 summer events each in 1975 and 1976. Forage production from control plots averaged only 200 kg/ha/year the second and third years. Forage yield was increased about ldfold over that of the control using a waxed-soil runoff area two times the crop growing area. Adjusting yields for the size of the bare runoff areas, the average yield increase for the system was still five times greater than that which would have been obtained from an uninterrupted planting of grass. Water-use efficiencies for this technique were comparable to those for irrigated grass.