Catalytic Pyrolysis of Methane to Hydrogen and High-value Carbon: Catalyst Synthesis and Screening

Abstract

The thesis attempts to screen literature as well as to synthesize effective catalyst for catalytically cracking methane to hydrogen and high value carbon, with the objective of maximizing methane conversion, catalyst stability, high value carbon yield. Based on thorough screening of literature, iron based monometallic and bimetallic catalysts supported on a commercial mesoporous activated carbon were synthesized and were subjected to a variety of advanced analytical characterization before and after the catalytic decomposition of methane. The experiments were performed with different catalyst at 850ºC at a total gas space velocity of 8000 mL/h gcat. Monometallic catalysts, were synthesized with metal loading of 20, 30 and 40 wt% covering different impregnation techniques namely wet impregnation, incipient impregnation and hydrothermal impregnation. The 30%Fe/AC prepared using a hydrothermal route showed better conversion, stability and resistance to fouling . The bimetallic catalyst were synthesized by doping 5 wt% promoter metal (Mo and Cu), in 30%Fe/AC. The methane conversion for Cu-Fe/AC catalyst was found to be inferior to monometallic Fe/AC, while the bimetallic Mo-Fe/AC exhibited better conversion and stability. . The addition of Mo allowed better dispersion of Fe particles and the formation of filamentous carbon and thereby, influencing the catalytic activity positively. However, an increase in the % loading of (10, 15 wt%) Mo, tend to deactivate faster due to amorphous carbon deposits that blocked the Fe active sites. Additionally, a 20%Ni-20%Fe/AC bimetallic catalyst was sythesized which exhibited a carbon yield of 106% and stability as compared to Fe/AC with a 33%. The better carbon diffusion characteristics in Ni-Fe alloy and the higher presence of fibrous carbon is believed to have played a role in the improved activity of Ni-Fe/AC.

Date of Award	Aug 2023
Original language	American English
Supervisor	SRINIVASA Chandrasekar (Supervisor)