Development of Oxydehydration Catalyst for Glycerol to Acrylic acid and Hydrogenation Catalyst of Carbon monoxide by Hetero-atom Doping Technique

Abstract

Over the past centuries, development of efficient catalyst for the production of fuel and fine chemicals using petroleum is one of the most important works in academic and industrial fields. As the emergence of new resources replacing fossil resources, such as biomass, shale gas, etc., new catalytic systems is highly required. Among various method to develop active catalysts, doping method have attracted attention due to its effectiveness for tuning surface properties. In this thesis, by doping hetero-atom, bi-functional catalyst for the production of value-added chemicals from biomass-derived reactant was developed, and catalytic activity was controlled by manipulating electronic properties of catalysts. Oxydehydration of glycerol is currently attracting considerable attentions. In an attempt to develop efficient catalyst for the reaction, tungsten incorporated molybdenum vanadium mixed oxide (MoVW) catalysts were designed based on computational calculations and mechanistic insights. By incorporating tungsten into molybdenum vanadium mixed oxide (MoV) structure, the catalysts are active and selective in not only the dehydration of glycerol but also the subsequent oxidation of acrolein to acrylic acid. Structural characterization was performed by XRD, XANES, DFT calculations, Raman, and IR spectroscopies. The incorporated tungsten species enhanced the acid and redox properties of the catalyst, leading to a high selectivity to acrylic acid (30.5 %). It not only induced but also stabilized the reduced oxidation states of molybdenum and vanadium atoms, as confirmed by XPS and DFT calculations. Hence, a stable and selective production of acrylic acid was achieved with full glycerol conversion for 110 h. The MoVW catalytic system with an additional acid catalyst bed exhibited remarkable selectivity for acrylic acid (47.2 %), suggesting its potential for practical applications. In the fundamental aspect, catalytic activity in heterogeneous catalysis was controlled by tuning electronic state of a catalyst by doping method. For controlling the electronic state of metal supported graphene catalysts, type (N and B) and concentrations of dopants was varied. The change in electronic state of active metals was confirmed by XPS analysis. Although factors affecting on activity, such as particle size, phase, loading amount, were excluded among the prepared catalysts, different catalytic activities were observed. Theoretical calculations revealed that variation in interactions between active metal and reactant, induced by tuning the electronic state, affected catalytic activity of the catalysts.