Biomass pyrolysis and in-line air–steam reforming as a potential strategy to progress towards sustainable ammonia production
Irati García, María Cortazar, Laura Santamaria, Gartzen López, Javier Bilbao, Martı́n Olazar, Maider Amutio, Maite Artetxe
Abstract
• An environmentally friendly NH 3 production process from biomass was proposed. • A combined approach of simulation and experimentation was conducted. • A H 2 /N 2 ratio above 3 was obtained under autothermal conditions. • The ammonia production capacity of this novel process is 558 g NH 3 kg biomass −1 . • The results evidence the potential of biomass pyrolysis reforming for NH 3 synthesis. The steady growth in world population has increased the need for ammonia-derived products, especially fertilizers. Current ammonia production is highly energy intensive and emits huge amounts of CO 2 due to the use of natural gas. Therefore, progress on the sustainability of the process is urgently required. Biomass pyrolysis and in-line air–steam reforming is an encouraging process for the renewable and sustainable ammonia production. Thus, this work studies the potential of this process to produce a stream containing H 2 and N 2 (from the air) in a 3:1 ratio suitable for the Haber-Bosch process. First, a thermodynamic assessment was performed to ascertain the most suitable conditions to obtain a gas stream with a suitable H 2 /N 2 ratio. The simulations were carried out using AVEVA Pro II software by varying the amount of air ER (Equivalence Ratios from 0.13 to 0.17) incorporated into the inlet stream (mixture of air and steam) fed into the reformer of biomass volatiles. Based on the simulation results, the integrated process of biomass pyrolysis and in-line air–steam reforming was conducted in a bench-scale plant, which combines conical spouted bed reactor (CSBR) and fluidized bed reactor (FBR) technologies for the pyrolysis and air–steam reforming steps, respectively. The results showed that a H 2 /N 2 ratio above 3 may be achieved under autothermal conditions (ER = 0.13), which confirms the potential of the biomass pyrolysis and in-line air–steam reforming process for the sustainable production of ammonia. In fact, this innovative process allows the production of 558 g NH 3 kg biomass −1 .