Differences in Product Distribution Measured with Flame Ionization Detector Gas Chromatography and Thermal Conductivity Detector Gas Chromatography during the Dimethyl Ether-to-Olefins and Methanol-to-Olefins Processes

Abstract

It is generally accepted that the products of dimethyl ether (DME)-to-olefins (DTO) and methanol-to-olefins (MTO) processes are hydrocarbons; therefore, gas chromatography (GC) equipped with a flame ionization detector (FID) rather than a thermal conductivity detector (TCD) is usually used to measure their product distribution for the higher response sensitivity of FID than TCD. Product distributions of DTO and MTO processes over SAPO-34 and metal-oxide-modified SAPO-34 catalysts were measured in this research work with GC equipped with FID and TCD. Results showed that product distribution over SAPO-34 measured with FID GC alone was similar to that measured with TCD + FID GC when the DME or methanol conversions were close to 100% and the main products were hydrocarbons, with only trace amounts of H2 and carbon oxides in the products. When using metal-oxide-modified SAPO-34 as the catalyst, it was found that the product distribution measured by TCD + FID GC was greatly different from that measured by FID G...