Novel Approaches To The Production Of Higher Alcohols From Synthesis Gas Quarterly Report July 1 September 30 1993

This document reports work during this quarter on the project to produce higher alcohols from synthesis gas. A set of four methanol synthesis runs was conducted. Significant catalyst deactivation was experienced, and essentially all of the oil was lost from the reactor over the course of two weeks of operation. Three screening runs of potential high temperature oil were also conducted. However, essentially no oil remained in the reactor after completion of each run. A 1%Rh/1.3%Re/Al2O3 catalyst was prepared from Re and Rh carbonyls with the objective of obtaining intimate contact between Rh and Re atoms. The catalytic activity of this catalyst was explored. Mo was deposited on the catalyst from both molybdenum hexacarbonyl [Mo(CO)6] and (NH4)6Mo--O24·4H2O. The catalytic activity of the molybdenum promoted catalysts was found to be the highest achieved to date under this contract.

A detailed technical plan for research on higher-alcohol synthesis in a slurry reactor was prepared and approved internally, as part of the University's requirements for the doctoral degree. The focus of this plan is the high-pressure methanol synthesis catalyst, and modifications thereof. A major challenge of the research will be to identify a slurry medium that is stable at the typical operating temperature ofthis catalyst, i.e., about 400°C. Two shakedown runs were made in the stirred autoclave without catalyst in order to check the mechanical operation of the system and to test some of the analytical equipment. Further preparation, characterization and screening of higher-oxygenate synthesis catalysts based on rhodium were carried out. The catalyst compositions tested during the period were: Rh/Al2O3, Rh/Nb/Al2O3, Mo/Rh/Al2O3 and W/Rh/Al2O3. All catalysts contained a nominal 1 wt. % Rh. Rh/Nb/Al2O3 and Rh/Mo/Al2O3 were about twice as active for COconversion as the other catalysts. However, oxygenate yields were disappointing for all of the compositions tested. The Rh/Mo/Al2O3 catalyst had the highest carbon efficiency to oxygenates, 33%.

Standard thermal stability tests were carried out on four liquids: decahydroquinoline (DHQ); 1, 3-Di-4 piperidylpropane (134PPDP), Naphthenic Base 37 and tetrahydronaphthalene (tetralin). Tetralin was more stable than decahydronaphthalene (Decalin{reg_sign}), and THQ was slightly less stable. Both tetralin and THQ should be evaluated further as slurry liquids in the presence of catalyst and syngas. Naphthenic Base 37 and 134PPDP do not have satisfactory thermal stability. Vapor pressure osmometry (VPO) was shown to be an unreliable technique for measuring the average molecular weight of slurry liquids. Gas chromatography/mass spectroscopy (GUMS) is a more accurate technique for pure compounds.

Three runs were carried out in the continuous stirred autoclave reactor with Englehard Zn-0312 T 1/8 {open_quotes}zinc chromite{close_quotes} catalyst and with decahydronaphthalene (Decalin{reg_sign}) as the slurry liquid. One short run, which was prematurely terminated by operational problems, was designed to define the effect of stirrer speed on catalyst performance. Two longer runs completed the data base required for kinetic characterization of the unpromoted {open_quotes}zinc chromite{close_quotes} catalyst. Although analysis of the data is not complete, it is evident that: (1) stirrer speed has no significant effect on the measured reaction rate, and; (2) carbon dioxide appears to inhibit catalyst activity.