Propane CO2 (dry) reforming over bimetallic Mo–Ni/Al2O3 catalyst

An evaluative investigation of propane CO2 reforming over bimetallic alumina supported 5%Mo–10%Ni catalyst has been carried out in a fixed-bed reactor at 0.1 MPa and temperatures ranging from 823 to 973 K. Temperature-programmed calcination revealed the metal nitrate decomposition of Mo–Ni catalyst at around 475 K, while TPR analysis showed the complete reduction of fresh catalyst at 973 K. Physicochemical properties of Mo–Ni/Al2O3 catalyst were determined from N2-physisorption, H2-chemisorption, NH3 and CO2-temperature-programmed desorption as well as X-ray diffraction analysis. NH3-TPD analysis revealed that the Mo–Ni/Al2O3 catalyst surface was populated with weak and strong Lewis acid sites, while CO2-TPD showed only one peak assigned to weak Lewis basic site. Increased CO2 partial pressure in feed caused an initial increase in H2, CO, and CO2 reaction rates, peaked at stoichiometric feed ratio (R), CO2:C3H8, of 3 followed by a gentle decrease for R>3. H2:CO and CH4:CO experienced logarithmic decay with increased reactant ratio, while CO:CO2 ratio remained constant at 2. Time-on-stream analysis revealed that Mo–Ni is a stable and active catalyst at different temperatures during propane dry reforming. A global kinetic expression corresponding to carbon deposition was obtained over various feed compositions and temperatures. Post-reaction data from TPR–TPO–TPR–TPO confirmed the presence of at least two carbon pools, Cα and Cβ. The former, atomic carbon is reactive with H2 and the latter, dehydropolymerised and aged carbonaceous matter, is only removed by O2.

► NH3-TPD analysis confirmed the existence of weak and strong Lewis acid sites.
► Addition of Mo to Ni/Al2O3 reduced the BET surface area due to the pore blockage.
► CO2:C3H8=3 showed the highest H2, CO, and CO2 reaction rates.
► Mo–Ni catalyst showed a good stability over propane dry reforming.
► TPR–TPO schemes confirmed the existence of at least two types of carbon pools.