Effect of the Addition of Ethanol to Synthesis Gas on the Production of Higher Alcohols over Cs and Ru Modified Cu/ZnO Catalysts

Abstract

The addition of ethanol to synthesis gas and its influence on the production of higher alcohols (HA) was investigated over Cs– and Ru–Cu/ZnO catalysts at 320 °C and an initial pressure of 5.0 MPa in a batch reactor. A change in the reaction path from aldol-type condensation of C1-intermediates to homocoupling of ethanol was found upon increase of the ethanol to CO ratio. Furthermore, the productivity toward HA was enhanced for higher ethanol to CO ratios. The production of HA was maximized with the side products in an acceptable range for n EtOH:n CO = 0.5. Excess of ethanol gave lower production rates and leaching of the metals was observed. Cesium (0.3–1.0 mol %) proved to be a better dopant. Excess of Cs (3 mol %) led to a lower catalyst performance, probably due to a blockage of the active sites and a change in the reducibility of the catalyst.

Promotional Effects of Cesium Promoter on Higher Alcohol Synthesis from Syngas over Cesium-Promoted Cu/ZnO/Al2O3 Catalysts

“…It appears that the reaction temperature has no effect on the CGPs of C 3 * to 2-methyl-C 3 * because the difference in the CGPs over the Cs 2 O-promoted and unpromoted Cu/ZnO/ Al 2 O 3 catalysts is approximately 0 within the full temperature range, as shown in Figure 4c. In agreement with previous studies, 24,52 the fraction (not the productivity) of 2-methyl-1propanol in C 3+ OH is mainly affected by reaction temperature, not by the cesium promoter. The improvement in the productivity of C 3+ OH is attributed to a large amount of C 2 * derived from the initial C−C bond formation over the Cu/ ZnO/Al 2 O 3 catalysts modified with cesium promoter.…”

Effects of n‐Propanol Co‐feeding in Isobutanol Synthesis from Syngas over K‐CuMgCe Catalyst

“…The 2‐methyl‐3‐pentanol mainly formed via self‐condensation (β(R)) of intermediates derived from n‐propanol. Aldehydes and ketones were both intermediates that form alcohols and esters, and the formation of esters and alcohols was a competitive reaction [22,27] . Cu provided hydrogenation/dehydrogenation sites and CO adsorption sites, while K and Mg−Ce provided basic sites for aldol condensation.…”

Research progress of catalysts for synthesis of low-carbon alcohols from synthesis gas

“…Adding a small amount of Cr can signicantly increase the surface area of the catalyst, thereby inhibiting the agglomeration of active metals, which in turn makes the catalyst have better activity and stability. 22,23…”