DME-to-Hydrocarbon over an MFI Zeolite: Product Selectivity Controlled by Oxygenates under the Kinetic Regime

Abstract

The influence of process variables on the DME-to-hydrocarbon (DtH) conversion has been assessed. The reaction was studied at atmospheric pressure, over an MFI zeolite (H-ZSM-5, SiO2/Al2O3 = 58), in a gradientless recycle reactor, under the kinetic regime, and process variables in the range of 598–648 K and space time in the range of 0.008–0.040 h kgcat kgDME –1. The results showed that DME and methanol are not in equilibrium, that the cis-/trans-C4 olefins are in equilibrium with each other but not with the 1-butene, while C5 + hydrocarbons are favored at high oxygenates conversion. Finally, it was observed for the first time, to best of the knowledge of the current authors, that under kinetically controlled conditions, the selectivity to main groups of products can be described by the oxygenates conversion (x oxy), independently of the process conditions, which means that the x oxy controls the process selectivity independently of reaction temperature and space time.

The Oxygenate-Mediated Conversion of COx to Hydrocarbons─On the Role of Zeolites in Tandem Catalysis

“…Ortega and Kolb also studied the influence of process variables, specifically a temperature range between 325 and 375 °C and space time range between 0.008 and 0.040 h•kg cat /kg DME using a ZSM-5 (Si/Al = 58) catalyst. 175 Thorough data and kinetic analysis revealed that product selectivity was dependent on DME conversion and independent of reaction temperatures and space times. They further concluded that equilibrium was not reached between DME and methanol in this study, thereby supporting the earlier finding of Martinez-Espin et al 99 The Bhan group conceived several studies on olefins (i.e., ethylene, propylene, 1-butene, trans-butene, cis-butene, and isobutene) and aromatics (i.e., benzene, toluene, para-xylene, and ortho-xylene) methylation reactions using DME.…”

“…The lower steam partial pressure in DTH was suggested to be the cause for higher reactivity but also faster deactivation, presumably due to the high DME partial pressure. Ortega and Kolb also studied the influence of process variables, specifically a temperature range between 325 and 375 °C and space time range between 0.008 and 0.040 h·kg cat /kg DME using a ZSM-5 (Si/Al = 58) catalyst . Thorough data and kinetic analysis revealed that product selectivity was dependent on DME conversion and independent of reaction temperatures and space times.…”

Mechanistic kinetic modeling for catalytic conversion of DME to gasoline-range hydrocarbons over nanostructured ZSM-5

“…The conversion of dimethyl ether (DME) to hydrocarbons has received significant attention in terms of producing possible fuel chemicals from low-carbon reactants, along with the conversion of methanol. 1,2 Because this is a process that can produce alternative fuels for existing petrochemical-based fuels, it is important in situations where environmental and energy production transformation are a goal around the globe.…”