Process System Modeling of Large-Scale Energy Storage, CO2 and Biomass Based Formic Acid Production Systems

Abstract

Transition to renewable and alternative energy sources has become one of the most important subject of the decade. In The Netherlands today, 11.1% of the primary energy demand is obtained from renewable energy and the biomass accounts for 54% [1]. Another promising material for value added chemical synthesis is carbon dioxide. By utilization of CO2, the production of valuable chemical materials such as methanol, formic acid that can be used as a fuel, heat or power source and reducing the greenhouse gas effect by lowering emission levels will provide industrial and environmental advantages at the same time. Formic acid, used in the agriculture, pharmaceuticals and textile, is a key chemical that can also be used in energy conversion processes. In the current industrial practice, formic acid is produced by carbonylation of methanol with carbon monoxide. However, methanol is another value added chemical that is used in energy production, hence expensive for the process. Therefore, researchers started looking into alternative methods. Biomass and carbon dioxide utilization methods are two of them. In this thesis study, 10 kton and 100 kton annual production of 85 wt.% formic acid from wet oxidation of glucose and catalytic reduction of carbon dioxide, have been modeled and a techno-economic analysis is carried out. Additionally, the processes of obtaining glucose from lignocellulosic biomass and carbon dioxide from syngas by pre-combustion capture are also simulated. ASPEN Plus V8.8 process flowsheeting package program has been used for the simulations. From the results, in energy analysis biomass based formic acid synthesis process showed higher efficiency than CO2 based production. When the hydrogen peroxide and oxygen based biomass wet oxidation routes are compared, it is observed that oxygen based operation is more efficient than hydrogen peroxide based conversion because of lower utility requirements. It was determined that biomass based formic acid production can be economically profitable, but only for large scale wet oxidation via oxygen together with the sale of by-products obtained in pre-treatment process. On the contrary, no profit was obtained by the hydrogen peroxide route. In carbon dioxide utilization route, the breakeven selling price (BSP) of the formic acid was computed to be 7% more than the current market price. In order to improve the process, two case studies were created. In the first case, economically the most suitable reactor amount configuration is determined. However, the process was still not profitable. In the second case study, two times more active catalyst, Au=Al2O3, has been utilized. The process took half the residence time of the previous case and BSP value determined to be 2.6% lower than the current market price. Also, slight increase in efficiency is observed. In conclusion, more research should be done and experiments regarding reaction and intermediate substance performances should be conducted, in order to simulate the process more in detail. However, despite the uncertainties, in this era where the transition to greener energy production through the use of biomass and the reduction of carbon dioxide emissions have been made a definite target by the governments, the synthesis methods studied, will gain importance as the purposes of formic acid use increase.