(675g) Microwave-Assisted Pyrolysis of Coal-Biomass Mixturs UNDER Reactive Gases

Abdelsayed, V., National Energy Technology Laboratory
Shekhawat, D., National Energy Technology Laboratory
Smith, M., U.S. DOE NETL
Link, D., National Energy Technology Laboratory

Conversion of coal/biomass blends into higher value chemicals can either be achieved directly, by non-oxidative routes or indirectly, by oxidative routes. Usually, multiple chemical processes are involved in oxidative routes; first a gasification step is needed to produce syngas, followed by Fisher Tropsch reactions to produce chemicals. On the other hand, pyrolysis could be used as a single step process to convert these blends directly into chemicals. However, the main obstacle in conventional thermal pyrolysis is the formation of high molecular weight tars which is difficult to handle and require further cracking to be utilized. In this work, microwave-assisted pyrolysis was studied on samples of Mississippi lignite and PRB subB coals mixed with 25 wt% yellow pine wood sawdust. The microwave-assisted pyrolysis product distributions of the above blends were compared to those using conventional thermal pyrolysis.. Microwave energy was not only used for rapid heating but also to examine any possible kinetic enhancements of this process either under inert (N2) or reactive hydrogen rich (H2 and CH4) gases. Our initial GC-MS results suggested that the oil product distributions were shifted to relatively lower molecular weight chemicals using microwave heating compared to conventional heating. It also suggested that the addition of hydrogenated gases increases the oil yield produced. The chars produced were characterized by different techniques, such as SEM and XRD to determine the morphology and crystallinity of these samples before and after pyrolysis, respectively. The porosity of fresh and char samples were determined using N2-adsorption surface area measurements.