Novel membranes and catalysts reduce greenhouse gas emissions in chemical industry
C2H4 is produced in larger quantities than any other organic compound and much of it goes towards polyethylene, the most commonly used plastic today. In Europe the production of C2H4 is carried out through naphtha cracking, but this results in large quantities of carbon dioxide (CO2) as a by-product. One way to reduce CO2 output is to produce C2H4 from methane (CH4), which is more widely available, less polluting and cheaper than using naphtha. However, the process of converting methane to C2H4, known as oxidative coupling of methane (OCM), is not commercially viable because of its low yields. The EU-funded MEMERE project addressed this challenge by designing and testing a novel, membrane reactor for the direct conversion of CH4 into C2H4 using integrated air separation. The initiative aimed to increase the yield of ethylene while lowering production costs and reducing energy intensity and emissions compared to current state-of-the-art technologies. The researchers developed novel, cheap yet more resistant oxygen selective membranes for efficient air separation and distributive feeding of oxygen to the reactor. “The objective is to give a robust proof of concept and validation of the technology to Technology Ready Level 5 by designing, building, operating and validating a prototype module based on OCM technology that will be integrated in a mini-plant transported in a container,” states project coordinator Fausto Gallucci.
A new approach
Project partners focused on the air separation through reactor integrated mixed ionic-electronic conducting (MIECs) membranes within a reactor operated at high temperature for OCM. ”By combining different process steps in a single multifunctional unit we hoped to achieve much higher yields than with conventional reactors,” Gallucci, explains. In OCM there is the separation of oxygen, which is fed into the reactor through ceramic membranes, while the reaction occurs on a catalyst that is able to operate at low oxygen concentration. This combination enables higher yields and lower costs compared to standard technologies. The consortium therefore developed catalysts that are more stable under the reaction conditions and especially at low oxygen concentration and created membranes that can be used under reactive conditions. “We have developed porous magnesium oxide membranes for high temperature oxygen feeding. These have been scaled-up and tested. At the same time, we have developed dual and three phase membranes for oxygen separation in reactors where a large amount of CO2 is present, which is a poison for most of the O2 membranes currently available,” notes Gallucci.
Multiple benefits
MEMERE successfully produced a large amount of new knowledge from fundamental science to techno economic and life cycle analysis. According to Gallucci: “Our most exciting results include the way we have developed new technologies for membranes and 3D printed catalysts. At the same time a large number of PhD and MSc students were able to work directly on the technology in close collaboration with industry.” Improving the efficiency of the chemical industry will help Europe to become more competitive in the global marketplace thereby enabling it to invest in new more sustainable technologies and reduce greenhouse gas emissions. In addition, the project will benefit society, as new jobs will be created in both the membrane and catalyst fields and other industrial sectors. “MEMERE technology can also be used at the small-to-medium scale to convert CH4 produced in remote areas where conventional technologies cannot be currently exploited,” Gallucci concludes.
Keywords
MEMERE, membrane, reactor, methane (CH4), catalyst, carbon dioxide, oxidative coupling of methane (OCM)