Process simulation can reveal the optimum conditions for the process which consists of each unit operation, or theoretically investigates individual processes. The author has developed the 1,3-butadiene (1,3-BD) production process from lignin through simulation. The balance of payment (BP) was considered as an economic indicator of the process and was calculated based on mass balance and energy balance. This means the income from processing a unit weight of lignin. The process simulation indicated that the process via dimethyl ether (DME) exhibited the highest BP among the three proposed processes. The promising 1,3-BD production process consisted of lignin gasification, DME synthesis, n-butene synthesis, and isomerization/dehydrogenation. Considering lignin gasification power generation as a competitive process, the 1,3-BD production process was improved based on the BP. The enhancement of the n-butene yield from DME is a technical issue, and the catalytic performance for competitive economics was revealed through process simulation. The findings are an effective guideline for experimental verification. Process simulation and experimental verification play a complementary role in accelerating the commercialization of biomass conversion processes.

Cellulose is the largest inedible biomass resource on earth. To convert cellulose into a series of useful chemicals, we have developed catalytic reactions to convert cellulose into methyl levulinate and methyl lactate. Although both are multi-step reactions, these reactions proceeded efficiently by developing optimal catalysts for each of the elementary reactions and enabling them to work cooperatively. The combination of Brønsted acid and Lewis acid worked well for the synthesis of methyl levulinic acid, while the combination of different kinds of Lewis acids worked well for the synthesis of methyl lactate. Both levulinic acid and lactic acid have high potential in biomass refineries, and recent reactions to convert them to succinic acid, butene, BTX (benzene, toluene, and xylene), pentenoic acid and acrylic acid were reviewed.

The demand for alternative energy, materials, and technology to petrochemistry has been increasing due to environmental threats such as global warming. Here, we introduce microbial gas fermentation as a candidate technology to meet the demand. Gas fermentation can utilize syngas to produce valuable chemicals. Syngas is derived from biomass gasification and composed of mainly hydrogen and carbon monoxide. The gasification process can utilize any organic materials, including recalcitrant lignin and other organic wastes. Hence, it can contribute to solving the issue by utilizing carbon neutral resources and recycling various materials. In addition, gas fermentation can utilize carbon dioxide by supplementing hydrogen derived from renewable energy. The utilization of such gaseous substrates can be accomplished by a group of microorganisms called acetogen. We describe the metabolic pathway to utilize gaseous substrates, show some examples of the chemical production, and discuss the future perspective.