Catalytic conversion of glycerol with iron oxide-based catalysts was investigated for the production of useful chemicals. The catalytic reaction was carried out in a fixed-bed flow reactor at 623 K under atmospheric pressure. Useful chemicals such as allyl-alcohol, propylene and ketones were produced from glycerol through two main pathways: formation of allyl alcohol and propylene (Pathway I), and formation of hydroxyacetone and acrolein (Pathway II). Hydroxyacetone in Pathway II is easily converted into carboxylic acids followed by ketonization to form acetone, methyl ethyl ketone and pentanone. An increase in the W/F (weight ratio of catalyst to feedstock) value allowed the consecutive reactions to progress and the final products were 24 mol%-carbon of propylene and 25 mol%-carbon of ketones. Moreover, addition of alkaline metals to the catalyst increased the yield of allyl alcohol. This study demonstrates the production of useful chemicals from glycerol (crude glycerol and reagent glycerol). The effects of catalyst composition and experimental conditions on these yields are discussed, based on investigations of the reaction pathways and mechanisms.
According to difficulties of producing heavy oil reservoirs, in-situ combustion (ISC) as one of the high efficient methods leads to reduce oil viscosity by increasing temperature. Since there are remarkable amounts of heavy oil reservoirs in the world and lots of experimental works have been carried out on sandstones, shale or oil sands, the research on carbonate rocks seems to be rare. The experimental tests were performed with the oil of 17.5° API and 8° API mixed with the crushed carbonate rocks of Asmari and Sarvak formations respectively to investigate the feasibility of ISC and calculate its parameters. According to experiments, combustion tube conducted vertically to use gravity as a force to minimize gravity segregation effects. Results show that combustion is technically applicable to the both rock-fluid systems. Additionally the percentages of CO2, O2 and CO have been measured by gas analyzer. Moreover, the effect of grain size on combustion temperature, connate water on oil recovery and front characteristics are investigated. Finally, fractured model of combustion tube is simulated and the effects of air injection rate, permeability, initial oil saturation and grid size are investigated. The obtained basic parameters of experiments are suitable for ISC implementation to fields efficiently.
Ru–Sn/C catalysts were prepared by the conventional impregnation method and characterized by XRD, H2-TPR, visible light absorption, EDX and XPS. The combination of metal sources, RuCl3, Ru(NO)(NO3)3, Ru(NO3)3, SnCl2, SnCl4 and Sn(OCOCH3)2, significantly influenced the metal structure of the catalysts. Using RuCl3 and SnCl4 as the metal sources, no XRD peaks for metals were observed and high dispersion of metals was estimated. On the other hand, use of RuCl3 and SnCl2 or Ru(NO3)3 and Sn(OCOCH3)2 resulted in a distinct XRD pattern determined to be a RuSn intermetallic compound of body-centered cubic structure. Presumably a type of complex formed between RuCl3 and SnCl2 or Ru(NO3)3 and Sn(OCOCH3)2 during the impregnation procedure. Hydrogenation of lactic acid to 1,2-propanediol was investigated with a 200 mL autoclave between 150 °C and 200 °C under 2-6 MPa of hydrogen (initial pressure at room temperature). The catalyst prepared from RuCl3 and SnCl4 had superior activity compared to reported catalysts under the following reaction conditions; 0.55 M lactic acid, 150 °C, 5.7 MPa of hydrogen and 4 h with 0.80 g of 5 % Ru–5.9 % Sn/C catalyst. The yield and productivity of this catalyst were 99.0 % and 0.51 g g-cat−1 h−1 (6.7 mmol g-cat−1 h−1), respectively. The high yield was achieved because no substantial consecutive hydrogenation of 1,2-propanediol occurred on the binary catalyst.
Alanine solution (1.0-3.0 wt%) was gasified in supercritical water using a tubular reactor at a temperature of 500 to 650 °C and a pressure of 25 MPa for a residence time of 86-119 s and compared the gasification characteristic with our previous work, glycine. The identification and quantification of gaseous products were conducted by gas chromatography (GC) and the total organic carbon (TOC) in the aqueous phase was also determined. The carbon gasification efficiency of alanine rose with increasing reaction temperature and the gasification rate followed first order kinetics. It was well expressed with the Arrhenius equation. The gasification rate of alanine was identical to that of glycine. The effect of the methyl group in alanine is the production of methane and the dilution of nitrogen so that the alkaline effect is suppressed. The former explains the higher methane yield, and the latter results in a high carbon monoxide yield.
Co/ZrO2–SiO2 bimodal catalyst has higher activity and higher selectivity for the Fischer-Tropsch synthesis than conventional catalysts. This study investigated the catalyst support pore structure in detail, especially the formation of small pores with a model analysis. The analysis considered 10 wt% ZrO2–SiO2 and 20 wt% ZrO2–SiO2 bimodal catalyst supports with various loadings of ZrO2. Higher loadings of ZrO2 from 10 to 20 wt% decreased the large pore size from 59.8 to 56.7 nm, resulting in the promotion of the formation of small ZrO2 pores inside the large SiO2 pores. Interestingly, small pore size remained unchanged at 3.9 nm, irrespective of the ZrO2 loading, indicating that the small pore size was determined by the character of the ZrO2 nanoparticles participating in the self-assembly of ZrO2 nanoparticles inside the large SiO2 pores. A theoretical model of the agglutination of ZrO2 nanoparticles was established, and used to analyze the formation of small ZrO2 pores. The model suggested that 12 ZrO2 nanoparticles formed a unit cell with diamond lattice structure. The obtained small pore size and large pore size were very close to the experimental findings, and the calculated specific surface area and pore volume were also similar to the measured values.