Toward A Glycerol Based (Bio)refinery: Process Design, Simulation and Assessment of Chemocatalytic Production Paths

Acrylic acid is an important organic industrial chemical, widely used as a raw material in various production. Poly-acrylic acids have shown excellent performances for polymeric materials. The global consumption is expected to grow high up to around 8.2 million tonnes by 2020. The conventional way of producing acrylic acid is performed by the catalytic partial oxygenation process of propylene, which is derived from petroleum and natural gas. This process has been highly dependent on fossil fuels for over 40 years. Under the pressure of 2°C target and volatility of acrylic acid price due to changeable fossil fuels price, alternative methods of producing acrylic acid on industrial scale are required for breaking the "Carbon lock-in". Renewable resources, such as glucose and glycerol, seem to have big potential. In this project, crude glycerol is used as the feeding stock for producing acrylic acid with acrolein as the intermediate product; the crude glycerol is considered as the byproduct of biodiesel production. Two steps of chemical reaction are involved, namely dehydration and oxidation. Each step is assisted by one kind of highly efficient catalyst, which is selected based on former literature results. Purification process is necessary for achieving high purity of acrylic acid. The simulation is performed with software Aspen Plus ®. Simulation results show that 2.48 kg of crude glycerol can be converted to 1 kg of acrylic acid of 99.94% purity. Pinch analysis helps defining the maximum heat recovery target and helps lower the impact of environment and operating cost by 12-14%. The glycerol based production of acrylic acid is compared with the fossil based production of acrylic acid under EU operating conditions and a glucose based model using sugarcane or corn as feedstock. The comparison mainly suggests that: glycerol based production seems more competitive environmentally and economically than the glucose based one; the environmental impact is heavily influenced by the alternative use of glycerol as a waste from the biodiesel production. In places where crude glycerol can be used as fuel in incineration plants, it may be less environmental friendly to use it for chemical production with the current status of technology; in areas where glycerol can only be treated in conventional waste treatment plants, to use glycerol for value-added production of chemicals (e.g., acrylic acid) seems a very promising method. To this end, further in-depth research is needed towards an integrated (multi-product) glycerol biorefinery