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PROMOTED ZINC CHROMITE CATALYSTS FOR HIGHER ALCOHOL SYNTHESIS

Description: This report describes the analytical protocols that were developed during the last two years to analyze ''spent'' THQ (tetrahydroquinoline) slurry liquid. Identification of the components of the ''spent'' THQ should help to understand the influence of the slurry medium on the methanol synthesis reaction, and on other reactions with THQ as the slurry liquid. Silica gel liquid chromatography and high performance liquid chromatography (HPLC) were used to isolate and purify the major compounds in the ''spent'' slurry liquid. Gas chromatography/mass spectroscopy (GC/MS), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) were applied to identify the major compounds. Methyl-, dimethyl-, and trimethyl-THQ were found to comprise more than 80% of the ''spent'' liquid. The balance was various methylated indoles. A methyl group always is attached to the N atom in the ring structure. Speculative mechanisms are presented that may help to understand the interaction between the catalyst and the alkylated THQ slurry liquid, and the effect of liquid composition on the methanol synthesis reaction. A poster entitled ''Promoted Zinc Chromite Catalyst for Higher Alcohol Synthesis in a Slurry Reactor-2. Spent Liquid Analysis'' was presented at the AIChE National Meeting, Los Angeles, CA, Nov 12-17, 2000.
Date: June 15, 2001
Creator: Sun, Ms. Xiaolei & Roberts, Professor George W.
Partner: UNT Libraries Government Documents Department

PROMOTED ZINC CHROMITE CATALYSTS FOR HIGHER ALCOHOL SYNTHESIS

Description: During this reporting period, a ''zinc chromite'' catalyst promoted with 6 wt.% cesium (Cs) was evaluated at the following operating conditions: Temperature - 375 C and 400 C; Total Pressure--13.6 MPa (2000 psig); Gas Hourly Space Velocity (GHSV) - 5000 standard liters/kg(cat)-hr; and H{sub 2}/CO feed ratio--0.5, 1.0 and 2.0 mole/mole. Decahydronaphthalene (DHN) was used as the slurry liquid. The experiment lasted for twelve days of continuous operation. Unpromoted zinc chromite catalyst then was re-examined under the same operating conditions. Reproducible data was achieved with a continuous liquid make-up. Compared with unpromoted zinc chromite catalyst, 6 wt.% Cs-promoted catalyst shifted the product distribution from methanol to higher alcohols, even though methanol was still the major product. The effect of operating conditions was less important than the addition of promoter. However, it was observed that higher temperature favors higher alcohol synthesis, and that a higher H{sub 2}/CO ratio leads to lower oxygenates selectivity and higher hydrocarbons selectivity. These trends showed clearly with the Cs-promoted catalyst, but were not as prominent with the unpromoted catalyst. The slurry liquid did not decompose or alkylate to a measurable extent during either continuous, 12 - day experiment, even with the higher reactor temperature (400 C). There was a relatively significant loss of catalyst surface area during the experiment with the promoted catalyst, but not with the unpromoted catalyst.
Date: December 20, 2000
Creator: Sun, Ms. Xiaolei & Roberts, Professor George W.
Partner: UNT Libraries Government Documents Department

PROMOTED ZINC CHROMITE CATALYSTS FOR HIGHER ALCOHOL SYNTHESIS

Description: During this reporting period, a ''zinc chromite'' catalyst promoted with 6 wt.% cesium (Cs) was evaluated at the following conditions: Temperature--375 C; Total Pressure--6.8 MPa (1000 psig); Gas Hourly Space Velocity (GHSV) - 5000 standard liters/kg(cat)-hr, and; H{sub 2}/CO feed ratio--1.0 mole/mole. Decahydronaphthalene (DHN) was used as the slurry liquid. The experiment lasted for eight days of continuous operation. Although the experimental data once again did not exhibit the desired degree of consistency, the data did show that methanol was the primary reaction product. The slurry liquid did not decompose or alkylate to a measurable extent during the continuous 8-day experiment. There was a relatively significant loss of catalyst surface area during the experiment. Gas chromatography/mass spectrometry (GC/MS) analysis of various fractions of ''spent'' THQ was carried out. The fractions were prepared by silica gel liquid chromatography (LC). Chemical formuli and probable structures for each major compound were obtained. However, a higher degree of purification will be necessary to allow nuclear magnetic resonance (NMR) analysis to be used for definitive compound identification. A new Maxpro gas booster (DLE 15-75) was purchased because the existing Haskel gas booster once again developed a severe leak of carbon monoxide and hydrogen, and was judged to be unworthy of repair.
Date: August 29, 2000
Creator: Sun, Ms. Xiaolei & Roberts, Professor George W.
Partner: UNT Libraries Government Documents Department

PROMOTED ZINC CHROMITE CATALYSTS FOR HIGHER ALCOHOL SYNTHESIS

Description: Work during the report period was concentrated on developing analytical techniques. Thin-layer chromatography (TLC) was used in an attempt to define the best mobile phase to separate the components of ''spent'' tetrahydroquinoline by liquid chromatography in a silica gel column. Conditions have been defined for separating the light gases produced by the reaction of carbon monoxide (CO) and hydrogen (H{sub 2}) over promoted ''zinc chromite'' catalysts. This will be done with a temperature-programmed Carboxen-1000 column, using a thermal conductivity detector for analysis. A Petrocol DM 150 capillary column will be purchased to separate the heavier products, which will be analyzed using a flame ionization detector.
Date: June 21, 2000
Creator: Sun, Ms. Xiaolei & Roberts, Professor George W.
Partner: UNT Libraries Government Documents Department

REFORMULATION OF COAL-DERIVED TRANSPORTATION FUELS: SELECTIVE OXIDATION OF CARBON MONOXIDE ON METAL FOAM CATALYSTS

Description: Several different catalytic reactions must be carried out in order to convert hydrocarbons (or alcohols) into hydrogen for use as a fuel for polyelectrolyte membrane (PEM) fuel cells. Each reaction in the fuel-processing sequence has a different set of characteristics, which influences the type of catalyst support that should be used for that particular reaction. A wide range of supports are being evaluated for the various reactions in the fuel-processing scheme, including porous and non-porous particles, ceramic and metal straight-channel monoliths, and ceramic and metal monolithic foams. These different types of support have distinctly different transport characteristics. The best choice of support for a given reaction will depend on the design constraints for the system, e.g., allowable pressure drop, and on the characteristics of the reaction for which the catalyst is being designed. Three of the most important reaction characteristics are the intrinsic reaction rate, the exothermicity/endothermicity of the reaction, and the nature of the reaction network, e.g., whether more than one reaction takes place and, in the case of multiple reactions, the configuration of the network. Isotopic transient kinetic analysis was used to study the surface intermediates. The preferential oxidation of low concentrations of carbon monoxide in the presence of high concentrations of hydrogen (PROX) is an important final step in most fuel processor designs. Data on the behavior of straight-channel monoliths and foam monolith supports will be presented to illustrate some of the factors involved in choosing a support for this reaction.
Date: December 31, 2002
Creator: Chin, Mr. Paul; Sun, Dr. Xiaolei; Roberts, Professor George W.; Spivey, Professor James J.; Sirijarhuphan, Mr. Amornmart; Dr. James G. Goodwin, Jr. et al.
Partner: UNT Libraries Government Documents Department