(643c) Novel Catalytic Chemical Looping Process Technology for Utilization of CO2 for Acrylonitrile Production

The present work deals with the novel process of converting CO₂ to CO and acrylonitrile (ACN) using mixed metal oxide oxygen carriers via chemical looping in a PID micro reactor. The first step of the chemical looping process involves the reduction of CO₂ to CO at 500-650°C using the reduced metal oxide followed by ammoxidation of propylene (C₃H₆) and ammonia (NH₃) with the oxidized carrier at 500-600°C using the reduced metal oxide to produce ACN.

X-ray fluorescence (XRF), powder x-ray diffraction (XRD) and Tunneling electron microscopy (TEM) were used to characterize the synthesized catalysts for chemical compositions and crystallinity. Surface area was characterized by N₂-physisorption using the Brunauer-Emmett-Teller theory (BET). For best performing catalysts, oxidation of the reduced catalyst by CO₂ was characterized by CO₂ pulsed chemisorption. CO₂ to CO conversion was found to be 20-30% at 400-500°C and increased to 30-50% at 500-600°C. ACN yields ranging from 6-15% were achieved with ~ 20-40% conversion of propylene and ~ 20-25% of NH₃ conversion. Selectivity for ACN was observed to be 30-40% at 500-600°C. Acrolein was observed as a by-product in all 3 cycles, confirming chemical looping of oxygen from CO_2. ACN is produced primarily in the first cycle. This may be due to carbon deposition on the catalyst surface or loss of Lewis acidic sites, preventing NH₃ binding, selective oxidation, or insertion of nitrogen in the ammoxidation mechanism. Future work will focus on increasing the ACN yield from all the 3 cycles.