(344c) Economic and Environmental Potentials of Biofuel Production Process Using Biphasic Reactor - Cyclopentyl Methyl Ether As Organic Solvent for Xylose Upgrading.

Biofuels are a promising source of renewable energy because they can be used within the existing fossil-fuel system without requiring drastic modification. Numerous studies have investigated ways to improve the reaction performance of fuels produced from biomass. However, means of improving the efficiency of process design have yet to receive thorough consideration, although these processes may have significant impacts on the economics of the biofuel industry. This study proposes a complete, efficient process for general application to biodiesel production, using experimentally proven reactions and thermodynamic data. Detailed technoeconomic analyses of potential global warming potential are provided to assess the impacts of certain parameters on economics and warming potentials. The proposed process incorporates biphasic reactors, which can deliver high product yield from biomass-derived raw materials. The results of this study show that the levelized cost of biodiesel production is $3.66 gal^-1,and the corresponding global warming potential (GWP) is 57.18 gCO₂eq MJ^-1 for the base case. The production cost and GWP can reach $3.26 gal^-1 and 29.39 gCO₂eq MJ^-1 depending on the xylose concentration and the furfural yield. The feed costs of xylose and hydrogen account for more than 80% of the levelized cost of biodiesel production, using phasic reactions, meeting standards of economic viability. The steam utility required for refining products is another main contributor to the levelized cost. The steam utility also takes the largest portion of GWP, ranging from 33% to 65% of the total. These results indicate the importance of the properties of the reaction system in producing biodiesel.

The organic solvent should be immiscible with water over a wide range of water concentrations and should maintain a high yield of furfural in the biphasic reaction, even with little water in the diluted xylose to reduce the energy burden of the water removal. Finding а more suitable solvent may reduce the amount of make-up necessary, but a small amount is unavoidable. This leads to a conclusion that the processes with biphasic reactions are bound to a general type of separation process, which consist of a phase separator and two separation processes for a water-rich phase and a solvent-rich phase to recover furfural. Considering that distillation columns are the most reliable operating units for the industrial level of separation, the proposed design may provide a generic example of the furfural refinery process. In addition, the costs of a separation system for furfural isolation dominate the total biofuel production costs, excepting the feed costs, meaning that the cost reduction for the furfural refinery is vital for designing biofuel processes. In this context, the cyclopentyl methyl ether (CPME) shows the appropriate properties for serving as an organic solvent for biofuel production because it lowers the required energy for furfural separation by forming a wide range of immiscible liquid-liquid phase equilibria with water. This thermodynamic property of CPME facilitates high-purity, low-energy CPME recycling, lowering the impact of CPME on the economic feasibility of the proposed process. When CPME is mixed with water in a single phase, the separation of CPME requires intensive energy because the boiling points of water and CPME are similar, reflecting their low relative volatility. As a result, the remaining water content in the CPME-rich stream from the outlet of the phase separation unit for CPME recycle greatly affects the profitability of the process overall. As the proposed process uses diluted xylose as its source of produce biofuel, this dependence on water can be critical to the profit. Thus, to ensure the economic viability of the biofuel production process using biphasic reactions, a solvent with the proper thermodynamic properties (similar to those of CPME and that can be easily separated from water) should be developed. Otherwise, an efficient way of reducing the amount of water obtained from diluted xylose should be developed while maintaining a high furfural yield. In tandem with the amount of the biphasic solution, the sensitivity analyses suggest that the mixing ratio of it has critical impact on the practical potential of the process because they affect both of the separation efficiency and the reaction performances. Thus, care must be taken in adjusting the amount of the organic solvent depending on the xylose concentration in water to increase the profitability of the production process