Production of Renewable Acrylic Acid via Catalytic Dehydration of Lactic Acid: Mechanistic Studies and Catalysts Design

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Abstract Title: Production of green polymer precursors from biomass through catalytic dehydration of lactic acid to acrylic acidAs environmental concerns and the price of hydrocarbon-derived feedstocks and intermediates escalate on a continuing basis, the shift of the production of fuels and chemicals from fossil to renewable carbon sources not only makes economic sense due to price volatility and dwindling reserve of crude oil, but also is highly desirable from the environmental perspective by effectively reducing some CO2 emissions. Acrylic acid and its esters are key precursors in the polymer industry, with an annual demand of 4 million metric tons. They are currently produced through an energy intensive crude oil-based process. In addition, the explosive growth of natural gas production has led to a sudden increase in the use of natural gas relative to crude oil as a carbon source, has created significant gaps between the production capacity and demand of many key chemicals including propylene, the raw material for acrylic acid production. Fortunately, recent progress in the field of biomass conversion has made the production of various chemicals, such as renewable lactic acid, from biomass technologically feasible and economically competitive. Professor Bingjun Xu at the University of Delaware, proposes to develop the fundamental understanding to formulate a process for using this lactic acid as a green precursor to make acrylic acid. This award supports the research needed to answer the challenges of a shift to renewable, biomass-derived feedstocks. Production of acrylic acid from lactic acid via catalytic dehydration is potentially more selective compared to the current industrial route due to the structural similarity of lactic and acrylic acids. In contrast to the current industrial process, which requires several selective oxidation steps starting from propylene, only one dehydration step is needed to convert lactic acid to acrylic acid. Thus catalysts and reaction condition can be optimized for a single step rather than many reactions, which typically occur on different type of active sites and reach optimal performance under different conditions. In addition, it is generally easier to control selectivities in dehydration than partial oxidation reactions, since total oxidation is typically more thermodynamically favored than partial oxidation reactions. The proposed work aims at rationally designing efficient catalysts to facilitate the conversion of lactic acid to acrylic acid through a combination of reactivity evaluations, materials synthesis and spectroscopic investigations. The study of catalytic dehydration of lactic acid to acrylic acid will also provide fundamental insights into the interaction and selective activation of bi- or multi-functional molecules, a group to which most biomass-derived molecules belong, with catalytic active sites. Thus, the mechanistic insights gained in the proposed research could lead to guiding principles for tailoring active sites of catalysts, not only for the specific reaction of dehydration of lactic acid, but also for a broad range of other chemical transformations involving multifunctional biomass-derived molecules.