Development studies on conversion of methanol and related oxygenates to gasoline. Quarterly progress report No. 4, November 1975--January 1976

Abstract

Five cycles of a long-term aging test in the fixed bed pilot plant have been successfully completed. The total on-stream time is over 100 days. In addition, catalyst performance is still very good. This test is being conducted at a higher recycle ratio, lower conversion reactor temperature, and lower space velocity than employed in the previous aging test. The lower steam partial pressure (resulting from higher recycle ratio) and lower reactor temperature reduce catalyst deactivation due to steaming. The milder operating conditions of the current aging test have substantially improved gasoline stability. Additive concentrations of 5 lb metal deactivator plus 15 lb antioxidant per 1000 bbl have inhibited gum formation in potential gum tests to low and acceptable levels even beyond methanol breakthrough. Lower concentrations of 1 lb metal deactivator plus 2.5 lb antioxidant per 1000 bbl also provided adequate protection until near methanol breakthrough. The temperature profiles in the catalyst bed during the aging test have revealed a well-defined reaction band in which there is a sharp temperature rise. The reaction band moves through the catalyst bed during each cycle. The kinetic model for methanol conversion, which was originally developed for the fluid bed reactor, has been extended to the fixed bed reactor. The results have provided an estimate of the ratio of the conversion efficiencies of the two different types of reactors. The relative efficiencies are comparable to those observed for other processes. The feasibility of operating with durene recycle has been experimentally demonstrated in a fixed bed pilot plant (single reactor). The results indicate that durene production can be reduced by this type of operation. Also, durene recycle has no apparent deleterious effects on catalyst performance (cycle length) or product yields.