Enhanced Oxidative Dehydrogenation of Ethane with Facilitated Transport Membranes for Low Cost Production of Ethylene

Ethylene demand is expected to increase by 50% domestically and worldwide over the next 5 years with a scramble to increase supply via expansion or grass root facilities. US capacity will remain at about 20% of the world’s supply and exceed 100 BPPY. To meet this challenge, US-DOE has invented a mixed metal oxide catalyst, M1 for the oxidative dehydrogenation of ethane (C2-ODH) to ethylene at high conversions and very high selectivities. Yields which historically only reached about 50% per mass of ethane feedstock will now exceed 90% with the M1 catalyst (C2-ODH-m). The process, now exothermic and low temperature may be run in a packed bed with cooling. Other operating conditions are low pressures and residence times of several seconds. Overall Objective: Conventional recovery and purification of ethylene would include compression, chilling, and sizable distillation columns. These systems are capital and energy intensive. C2-ODH-m technology will require none of those unit operations, only requiring 3 major systems; a reactor, heat management, and an ethylene recovery system using membranes. Capital costs are much lower, estimated <50% of conventional steam pyrolysis. Operating costs may be non-existent as the heat of reaction may be employed to power the plant. Additionally, the reactor effluent composition and conditions from C2-ODH-m integrates well with Compact Membrane Systems (CMS) Facilitated Transport Membrane (FTM). Operating at near ambient temperatures for ethylene-ethane separation high purity ethylene can be recovery with minimal infrastructure and operating costs. Phase I Results: Phase I experimental work and process analysis have been very successful. Custom fluoropolymers (CFP) have been synthesized and fabricated into composite membranes and show excellent flux and separation at ODH operating conditions. These excellent results are due to CMS’s CFP FTM and the low ethylene activity from the ODH process. CMS collaborating with Dr. Jerry Maffia completed detailed an economic evaluation showing that ODH/CMS membranes provide superb economics. Specifically CMS membranes taking 25% ethylene from ODH process will make Polymer Grade Ethylene (PGE) significantly cheaper than ODH plus distillation. Equally important, the ODH/membrane process for making PGE is less expensive than existing alternatives. This is the first time that membrane processes are projected to be less expensive than distillation for greenfield PGE operation. This success is due to the superior CMS CFP FTM with ideal conditions of the ODH reactor effluent. Phase II Plan: Phase II will focus on scaling up CMS CFP FTM and integrating with simulated ODH feed. CMS will also work closely with ODH and catalyst companies in order to integrate whole package. CMS has also received strong interest from large American membrane players. Commercial Applications and Other Benefits: The program will enhance low-cost synthesis of ethylene from shale gas based ethane. This creates significant value-added products from ethane.