Allyl Alcohol Production by Conversion of Glycerol Over Supported Iron and Nickel Bimetallic Oxides

Abstract

Abstract. The study of catalysts based on iron, nickel, and iron-nickel oxides (Fe, Ni and FeNi) supported on a commercial mesoporous alumina is presented. The metal oxides were synthesized by the incipient wetness impregnation method. The samples were characterized by XRD, TPR-H2, Raman spectroscopy, XPS and N2 adsorption. The catalytic activity was evaluated in the dehydration-dehydrogenation reaction of glycerol in the gas phase. In the iron oxide and nickel oxide catalysts, the result of TPR-H2 showed that the presence of nickel influences the reduction of iron species. In the reaction, the catalysts showed similar conversion. However, the selectivity of the bimetallic oxide catalysts is modified, and the production of allyl alcohol increases noticeably forming a greater amount allyl alcohol than that observed in the monometallic oxides, in which a greater amount of hydroxyacetone is formed. The results indicate that the redox pairs Fe+3/Fe+2 influence the selectivity of these oxides. A decrease in the ratio Fe+3/Fe+2 species favored the formation of allyl alcohol.
 
 Resumen. Se presenta el estudio de catalizadores basados en óxidos de hierro y níquel (Fe, Ni y FeNi) soportados en una alúmina mesoporosa comercial. Los óxidos metálicos se sintetizaron por el método de impregnación de humedad incipiente. Las muestras se caracterizaron por XRD, TPR-H2, espectroscopía Raman, XPS y adsorción de N2. La actividad catalítica se evaluó en la reacción de deshidratación-deshidrogenación de glicerol en la fase gaseosa. En los catalizadores de óxido de hierro y óxido de níquel, el resultado de TPR-H2 mostró que la presencia de níquel influye en la reducción de las especies de hierro. En la reacción, los catalizadores mostraron una conversión similar. Sin embargo, la selectividad en los catalizadores de óxidos bimetálicos se modifica formando una mayor cantidad de alcohol alílico que la observada en los óxidos monometálicos, donde se forma una mayor cantidad de hidroxiacetona. Los resultados obtenidos indican que los pares redox Fe+2/Fe+3 influyen en el comportamiento catalítico de estos óxidos, en la selectividad. Una disminución de la relación Fe+3/Fe+2 favorece la formación de alcohol alílico.

Transition Metal Catalysts for the Glycerol Reduction: Recent Advances

“…Moreover, the combination of the two metals changed the selectivity towards the AA (90 % GL conversion and 90 % AA selectivity) whereas with the monometallic oxides, 88 % HAc selectivity was reported. [140] The addition of potassium species to α-Fe 2 O 3 yielded a loss of LAS and, in the presence of formic acid, morphology changes of solid were observed with the formation of BAS. [141] Using these catalysts in the dehydration of GL at 623 K, AA was obtained as the main product (40 % yield, Acr 10 %, others 25 %).…”

“…The authors observed that, in these bimetallic catalysts, the presence of nickel reduced the iron oxidation state, enhancing the redox properties of the solid. Moreover, the combination of the two metals changed the selectivity towards the AA (90 % GL conversion and 90 % AA selectivity) whereas with the monometallic oxides, 88 % HAc selectivity was reported [140] . The addition of potassium species to α‐Fe 2 O 3 yielded a loss of LAS and, in the presence of formic acid, morphology changes of solid were observed with the formation of BAS [141] .…”

“…[139] Martín et al presented Fe, Ni and FeNi oxides supported on commercial mesoporous alumina as catalysts in the dehydration-dehydrogenation reaction of gas phase GL at 573 K and ambient pressure. [140] The authors observed that, in these bimetallic catalysts, the presence of nickel reduced the iron oxidation state, enhancing the redox properties of the solid. Moreover, the combination of the two metals changed the selectivity towards the AA (90 % GL conversion and 90 % AA selectivity) whereas with the monometallic oxides, 88 % HAc selectivity was reported.…”

“…Martín et al . presented Fe, Ni and FeNi oxides supported on commercial mesoporous alumina as catalysts in the dehydration‐dehydrogenation reaction of gas phase GL at 573 K and ambient pressure [140] . The authors observed that, in these bimetallic catalysts, the presence of nickel reduced the iron oxidation state, enhancing the redox properties of the solid.…”