Hydrogenolysis of Glycerol in Gas Phase on Cu-Cr Mixed Oxide Catalyst Doped with Ni (original) (raw)
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Catalysis Today, 2012
Cu based catalysts were prepared by co-precipitation, alkali fusion followed by precipitation and direct solid state fusion methods. The changes in the phase formation, morphology, crystallite size, extent of aggregation, strength and nature of acid sites were observed due to variations in precipitating agents and also their order of addition. The catalyst prepared by co-precipitation using Na 2 CO 3 showed the predominant presence of metallic Cu phase with a crystallite size of 5 nm, well segregated spherical morphology and highest acidity in the activated sample. These intrinsic properties contributed to achieve the highest glycerol conversion of 62% and 1,2-PDO selectivity of 88% in glycerol hydrogenolysis.
International Journal of Chemical Reactor Engineering, 2000
A series of Cu, Ni monometallic and bimetallic catalysts supported on γ-Al 2 O 3 and activated carbon were synthesized by incipient wetness impregnation method and examined for hydrogenolysis and esterification of glycerol. Hydrogenolysis reaction was carried out in a 250 ml Tefloncoated stainless steel batch reactor at 250°C and 10 bar H 2 pressure, whereas esterification of glycerol with acetic acid was carried out at 120°C at atmospheric pressure. The physiochemical properties of the catalysts were investigated by various techniques such as surface area, X-ray diffraction (XRD), NH 3 -temperature-programmed desorption (TPD). Characterization results dictated that the reduction behavior, acidic nature and the metal support interactions were varied with the support as well as Cu/Ni weight ratio. The XRD results confirmed the formation of mixed oxide Cu 0.75 Ni 0.25 Al 2 O 4 phase in Cu-Ni (3:1)/γ-Al 2 O 3 catalyst. Among the catalysts tested, Cu-Ni bimetallic catalysts showed superior performance as compared to monometallic catalysts in both the reactions. The glycerol hydrogenolysis activity of γ-Al 2 O 3 supported Cu-Ni catalysts was higher than the activated carbon-supported catalysts. 1,2-PDO was obtained as the main hydrogenolysis product independent of the support as well as Cu/Ni weight ratio and its selectivity was in the range of 92.8-98.5%. The acidic nature of γ-Al 2 O 3 and the mixed oxide (Cu 0.75 Ni 0.25 Al 2 O 4 ) phase played an important role for hydrogenolysis activity. Cu-Ni (3:1)/γ-Al 2 O 3 catalyst showed the maximum 1,2-PDO selectivity to 97% with 27% glycerol conversion after a reaction time of 5 h. On the other hand, Cu-Ni(1:3)/C catalyst showed the highest glycerol conversion of 97.4% for esterification and obtained selectivity to monoacetin, diacetin and triacetin were 26.1%, 67.2% and 6.5%, respectively.
Research on Chemical Intermediates, 2015
The aim of the present study is to investigate the influence of the support and composition of the active bimetallic phase on both the physicochemical and catalytic properties of catalysts for use in glycerol hydrogenolysis reaction. Two series of catalysts with different amounts of copper oxide and/or silver supported on Al 2 O 3 or TiO 2 oxides were prepared. To determine the physicochemical properties of the catalysts, the following techniques were used: Brunauer-Emmett-Teller, reactive N 2 O adsorption, X-ray diffraction, and temperature-programmed reduction TPR-H 2. Physicochemical characterization revealed that addition of silver modifies the redox properties of the catalysts containing copper oxide and influences their specific surface area. It was found that the type of carrier determines the catalytic activity and selectivities for desired products, strongly influencing their distribution. The Al 2 O 3-supported catalysts were much more selective for 1,2-propanediol, whereas 1-propanol was the main reaction product for the titania-supported catalysts. The best catalysts (6Cu/Al and 2Cu/Ti) achieved 38 % glycerol conversion with 71 % selectivity for 1,2-propanediol and 44 % conversion with 62 % selectivity for 1-propanol, respectively.
Hydrogen production by steam reforming of glycerol over Ni/Ce/Cu hydroxyapatite-supported catalysts
The depleting fossil fuels with their ever increasing prices have paved ways for alternative fuels. Use of biodiesel and its production are expected to grow steadily in future. With the increase in production of biodiesel, there would be a glut of glycerol in the world market. Glycerol is a potential feed stock for hydrogen production because one mole of glycerol on steam reforming produces 7 moles of hydrogen. Production of hydrogen from glycerol is environmentally friendly because it adds value to glycerol generated from biodiesel plants. The study focuses on comparison on Cobalt Catalyst and Nickel based catalysts modified with Mg on Alumina support. The catalysts were prepared by the incipient wetness technique. The experiments were carried out using lab scale catalytic reactor and the gas products generated are analyzed in GC. The paper discusses the effect of the catalysts on hydrogen selectivity and Conversion and glycerol conversion ranging from 700ºC to 900ºC. The effect of glycerol to water ratio, metal loading, temperature and feed flow rate was analyzed. It was found that with the increase in the water to glycerol molar ratio, feed flow rates around 1 ml/min, at 850ºC maximum hydrogen was produced. The results show that glycerol steam reforming is a viable alternative use of glycerol to produce hydrogen. A Theory regarding Kinetic Study and Characterisation of Liquid samples has been studied.
Hydrogenolysis of glycerol over Ni, Cu, Zn, and Zr supported on H-beta
Chemical Engineering Journal, 2017
A series of transition metal oxides (e.g., Ni, Cu, Zn, and Zr) were supported on H-beta with loading of 5-20 wt% via wet impregnation. These catalysts were evaluated in the hydrogenolysis of glycerol under aqueous conditions at different reaction temperatures (150-250 o C), times (5-15 h) and H 2 pressures (300-1200 psi). The results from characterization of materials by XRD, FT-IR, N 2 sorption and NH 3-TPD together with the results from the activity test allowed further understanding of the role of transition metals and acid sites on hydrogenolysis of glycerol. The H-beta was found to contain higher Brønsted acidity and catalyst activity compared to those supported metal catalysts. It was found that the acidic properties of the H-Beta zeolite and metal content play a significant role on the final product distribution. The major product over bare H-beta and Zr/H-beta was 1-proponal, while the concentration of 1,2-propanediol and 1,3-propanediol increased significantly by the incorporation of a second metal oxide. A high 1,3-propanediol selectivity of 14% was obtained over the H-beta supported Ni-Zr catalyst at 73% glycerol conversion. The selectivity of 1,2-propanediol and 1,3-propanediol were decreased at higher reaction temperature and time.
Cu–Zn–Al mixed oxides as catalysts for the hydrogenolysis of glycerol to 1,2-propanediol
Reaction Kinetics, Mechanisms and Catalysis, 2019
This study is aimed to compare Cu-Al-Zn catalysts prepared by different methods and their effectiveness in glycerol hydrogenolysis to 1,2-propanediol. The preparation methods were: co-precipitation and thermal decomposition of hydrotalcite, coprecipitation by KOH and thermal decomposition of the precipitate, sol-gel autocombustion method, oxalate-gel co-precipitation and thermal decomposition of the precipitate and finally, mechanical mixing of Cu, Zn, Al oxides. It was found that the activity of the catalysts correlates well with the size of Cu crystallites. The smaller Cu crystallites, the higher the activity. However, also the texture of the catalyst, which also depends on the preparation method, has an impact on the catalyst activity. On the other hand, no correlation between activity and acidity, as well as internal surface area was found.
Selective Hydrogenolysis of Glycerol to 1, 2 Propanediol Over Cu–ZnO Catalysts
Catalysis Letters, 2008
A series of Cu-ZnO catalysts with varying Cu to Zn weight ratio are prepared by co-precipitation method. The catalysts were characterized by surface area, XRD, TPR and N 2 O chemisorption to measure Cu metal area. These catalysts were evaluated for hydrogenolysis of glycerol. The catalyst with Cu to Zn ratio of 50:50 is highly active under relatively low H 2 pressure. The catalysts are highly selective towards 1,2 propanediol ([93%). The glycerol conversion depends upon the bifunctional nature of catalyst where it requires both acidic sites and metal surface. The presence of sufficient amount with small particle size of ZnO and Cu are required for high conversion of glycerol and selectivity to 1,2 propanediol. Different reaction parameters are studied in order to optimize the reaction conditions.