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Hydrogenation Catalysts
Published in Alvin B. Stiles, Theodore A. Koch, Catalyst Manufacture, 2019
Alvin B. Stiles, Theodore A. Koch
Copper chromite is one of the most effective catalysts for the hydrogenation of esters to produce alcohols without excessive hydrogenation to hydrocarbons. Copper chromite was one of the first spinel-type catalysts produced and has been very useful for the operation in question. The preparative method is as follows: A solution is prepared containing 0.5 M concentration of copper as nitrate and 0.5 M chromic acid as CrO3.This solution is heated to 30°C and rapidly agitated in a vessel such as that shown in Fig. 9. While at this temperature and being vigorously agitated, anhydrous ammonia is bubbled into the system until a pH of approximately 6.8 is reached. Under these conditions, the copper is precipitated as a complex usually identified as a basic copper ammonium chromate [Cu(NH4)3OH CrO4].
A Review of the Research
Published in Ozcan Konur, Biodiesel Fuels, 2021
Dasari et al. (2005) study the low-pressure hydrogenolysis of glycerol to propylene glycol in a paper with 642 citations. They use nickel, palladium, platinum, copper, and copper-chromite catalysts. They find that at temperatures above 200°C and a hydrogen pressure of 200 psi, the selectivity to propylene glycol decreased due to excessive hydrogenolysis of the propylene glycol. At 200 psi and 200°C the pressures and temperatures were significantly lower than those reported in the literature while maintaining high selectivities and good conversions. The yield of propylene glycol increased with decreasing water content. They validate a new reaction pathway for converting glycerol to propylene glycol via an intermediate by isolating the acetol intermediate.
Metal Incorporation into Copper Aluminum Borates
Published in John R. Kosak, Thomas A. Johnson, Catalysis of Organic Reactions, 2020
Larry C. Satek, Patrick E. McMahon
Copper chromite is used industrially for alcohol dehydrogenations, and gives initial results similar to the copper aluminum borates. However, copper chromite deactivates rapidly for 1-propanol conversion (11% conversion loss in 20 h).
Recent developments and potential advancement in the kinetics of catalytic oxidation of glycerol
Published in Chemical Engineering Communications, 2020
Rozaini Abdullah, Syamima Nasrin Mohamed Saleh, Kartina Embong, Ahmad Zuhairi Abdullah
In the following year, Liu and Ye (2015) further extended their study where they conducted their experiment using different copper-containing catalysts and barium promoted copper chromite (Ba-Cu2Cr2O5) to be coupled with CaO. Cu2O presented a significant value of LA yield (48.2%) followed by Ba-Cu2Cr2O5 (40.4%). Cu2O could be classified as an active catalyst for the dehydrogenation step. The report clearly stated that improved catalytic performance was observed upon addition of Cu2O on CaO; more than 50% LA with more than 90% conversion of glycerol were achieved. Moreover, the catalyst showed excellent performance even after two cycles of reaction after regeneration. As a conclusion, Cu2O-on-CaO was proven a potential catalyst for this reaction.
Effect of Long-Chain Bonding Agent on the Combustion of Composite Propellant and Modification of Combustion Performance Using Nano Additives
Published in Combustion Science and Technology, 2021
As the addition of nano-copper chromite with small weight percentage to propellant formulations based on MAPO as a bonding agent has a remarkable effect on the pressure exponent and thermal coefficient in which the value of (n) increased but still giving plateau-burning, taking in consideration also the increase in the thermal coefficient in which the heat transfer to the propellant layers increased also, caused improving in the combustion of the composite propellant. In group (f) which contains F1, F12, F13 and F14, in these formulations studied the effect of the addition of nano-copper chromite with MST as bonding agent as by adding nano-copper chromite instead of large size of aluminium by the weight percentage from 0.25%, 0.5%, and 0.75% the burning rate increased by 121.1%, 123.7%, 132.1%, respectively, in order as shown in Figure (18). In these formulations the effect of the addition of nano-copper chromite with small weight percentage to composite propellant is increasing the propellant surface area in the propellant itself as well as decreased the decomposition temperate of the oxidizer which affected on the speed of burning on the surface of the propellant and as result of that the burning rate increased. Adding small weight percentage nano-copper chromite has an effect on the propellant formulations based on MST as a bonding agent in which the value of pressure exponent is reduced causing a plateau-burning to propellant formulations, and also the slightly decreasing in the thermal coefficient due to the nature of copper chromite as increasing the heat transfer to the propellant layers which helps in increasing the thermal dissociation of the binder content including the bonding agent and released heat help in improving the combustion of the composite propellant.