Effect of Ni Dopant on Furan Activation over Mo2C Surface: Insights from First-Principles-Based Microkinetic Modeling

摘要

The role of Ni dopant in a molybdenum carbide (Mo2C) catalyst for butadiene and propyne production from furan is investigated by using a Mo2C(001) surface model and first-principles-based microkinetic modeling (MKM). A reaction mechanism including 18 reaction steps is generated to compute the turnover frequency (TOF) of butadiene and propyne from furan gas. The butadiene production is dominant with the TOF being 3-6 orders of magnitude higher than the TOF of propyne on a bare Mo2C surface due to an active C-O bond scission reaction compared to C-C bond cleavage reaction. The exothermic binding of ring-opened furan (CHCHCHCHO*) inhibits the activity of a bare Mo2C surface for butadiene and propyne production. Calculations predict that Mo2C surface modification with a Ni dopant energetically destabilizes the adsorption of CHCHCHCHO*, which facilitates the formation of butadiene and propyne. In the presence of Ni dopants on a Mo2C(001) surface, the selectivity toward the butadiene formation is decreased compared to propyne due to relatively favorable C-C bond scission as opposed to the C-O bond scission. This first-principles-based study provides mechanistic and kinetic insights into the role of dopants in cost-efficient Mo2C catalysts during the vapor phase conversion of furan to gaseous products.