Research On CH₄-CO₂Reforming Effects Caused By Microwave-induced Metal Discharge

The rapid development of technology is quite obvious as the era of information coming up. Thanks to this, the updating cycle of electric and electronic products keeps reducing, and working life gets shortened sharply. These lead to an significant increase in the number of discarded e-products. Waste electric and electronic equipment(WEEE) has already been the fastest-growing solid castoff all over the world. As the saying goes, garbage is a kind of misplaced resource. People begin to put their attention to the huge potential of resource recycling that hide in electronic wastes as their resource consciousness wake up. On the other hand, the heavy metals and toxic organic matter contained in WEEE cannot be ignored. Environmental security and human health are under threat because of application of outmoded disposal technology. It’s urgent to find out a kind of efficient and environmental friendly technology to get resource recycled and avoid pollution during the process of WEEE disposal. Microwave pyrolysis is now widely concerned as a promising recovery and utilization technology for large-scale application. The selective and volumetric features of microwave heating are coupled well with the complex electronic offal for the disposal of WEEE.Electric discharge was found during our research of WEEE pyrolysis induced by microwave. This phenomenon is due to the interaction between metal component. It could enhance pyrolysis process, and lead to a change of yield and composition of gaseous product. The volume of CH4and CO2reduces but volume of H2and CO increases to a great extent when compared with the gaseous product that there is no metal discharge during pyrolysis process. The gaseous product is more worth of recycling since the improvement of its quality. In this thesis, the author focused on this situation, shaped metal discharge phenomenon under microwave irradiation, studied the effect law of influence factors which could change metal discharge, and then did preliminary investigation on catalytic reforming effect of CH4and CO2 caused by metal discharge. This will promote the optimizing and application of microwave-induced WEEE pyrolysis.The author designed experiments elaborately to shape metal discharge under microwave irradiation. We did research to discover how the influencing factors worked on the initiation and intensity of metal discharge. Then the catalytic reforming effect of CH4and CO2caused by metal discharge was studied based on this. In this thesis, we took the whole process from the initiation of metal discharge till the end as research object to avoid interference caused by discharge instability. Influence factors include power of microwave generator, property of metal used for discharge initiating, property of atmosphere in which discharge occurs. The author found that discharge occurs much more frequently with high output power of microwave generator, and the discharge intensity is higher meanwhile. It’s much easier to trigger off metal discharge using a piece of irregular shaped metal strip with high length-width ratio, and the discharge intensity is positively related with metal strip numbers. Under atmosphere that is easy to ionized, discharge occurs easier, too. For example, discharge intensity under Ar atmosphere is higher than that under N2atmosphere, and the difference becomes obvious when the output power of microwave generator is low. We also found that once there is high intensity metal discharge, there is better gas catalytic reforming results because of the high energy that attached to gas system.At last, the simulation of gas reforming was carried out to verify the correctness of experiments. The author simulated the gas reaction under same thermal condition of actual experiments by Aspen plus, according to the previous research on heating effect of metal discharge. The simulated results showed good agreement with experimental data in term of varying pattern as the ratio of CH4changesThrough this thesis, the occurrence regularity of metal discharge under microwave irradiation was discovered preliminary. We got furtherer understanding on the reforming effect of CH4and CO2caused by metal discharge. Gas which is rich in CH4and CO2is quite common, so the research is of universality. This also points direction for future improvement of microwave-induced pyrolysis of WEEE.