Search

The enhancement of catalytic activity is always limited by the dilemma in activation and desorption due to Sabatier principle. Locating the Sabatier optimum by manipulating catalyst electronic structure has been a long‐standing challenge in heterogeneous catalysis. Herein, we presented a generic strategy to continuously tailor the Pt 5d state occupancy via tuning the PtOMn electronic linkage over Al2O3‐confined MnOx islands, aiming at accommodating the CH cleavage and product desorption capabilities in dehydrogenation of liquid organic hydrogen carriers (monocyclic/bicyclic hydrides). Rising Mn valence can decrease the Pt 5d state occupancy through more electron transfer from Pt 5d to O 2p due to the strong π‐donation of O 2p to Mn 3d. This will lead to the lower initial CH activation energy barrier while higher product desorption energy barrier. An intermediate Pt 5d filling of ~8.4 in PtMn2O3/Al2O3 enables the balanced level of product desorption and CH activation, thus ensuring a superior dehydrogenation activity. The electron structure‐adsorption‐performance modulation mechanism described herein provides a benchmark to locate the Sabatier optimum for the metal catalyst design. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-precious intermetallic compound catalysts for propane dehydrogenation. • Scaling relations are established using formation energies over terraces and steps. • Descriptor-based microkinetic analysis is carried out to obtain volcano curves. • Fe 3 Ga 1 is a good catalyst candidate with improved catalytic performance. By using a descriptor-based microkinetic analysis combined with results from density functional theory calculations over eight transition-metal (including Ni, Cu, Rh, Pd, Ag, Ir, Pt, and Au) terrace and stepped surfaces, intermetallic compounds have been screened to search for inexpensive and environmentally friendly propane dehydrogenation (PDH) catalysts with enhanced catalytic performance. Based on the scaling relations, the formation energies of ethyl on terrace and methylidyne on stepped surfaces are identified as two descriptors to represent the energetics of other reaction intermediates and transition sates. The derived PDH activity and propylene selectivity volcano curves not only provide a rational interpretation of the previously experimentally reported catalyst candidates, but also predict several unexpected binary combinations by screening 1482 A 3 B 1 and 741 A 1 B 1 intermetallic compounds. The non-precious Fe 3 Ga 1 is then synthesized and evaluated. Its improved propylene selectivity and catalytic stability with respect to those of the Pt catalyst validates the theoretical predictions experimentally. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atomically dispersed Pt-rTiO 2 catalyst shows good catalytic performance for PDH. • Single and dual Pt atoms can be tightly held by vacancies created on reduced TiO 2. • Dual-Pt-atom structure is the active ensemble for the C H bond activation. Tailoring atomically dispersed catalysts by various methods has been the subject of intense current research in heterogeneous catalysis. In this work, the structural stability and propane dehydrogenation performance of Pt-TiO 2 catalysts with single, dual, and triple Pt atoms doped on the reduced TiO 2 surface have been examined. Experimental results indicate the atomically dispersed Pt is thermally very stable and shows exceptionally high activity (TOF propane = 4.93 s−1) and selectivity (∼98.5 %) for the dehydrogenation reaction. The recently developed machine-learning-based SSW-NN method is then employed to explore the global potential energy surface of the atomically dispersed Pt atom-doped TiO 2 , which suggests that the single and dual Pt atoms can be tightly held by the vacancies created on the reduced transition-metal oxide, as confirmed by DFT + U calculated energetics. After that, advanced characterization techniques are used in conjunction with microkinetic analysis to establish the quantitative structure–activity relationships. It is found that the dual-Pt-atom structure with two Pt atoms embedded in adjacent Ti and O vacancies is the only active ensemble that dramatically promotes the C H bond activation and hydrogen recombination, as compared to single Pt atoms accommodated by either Ti or O vacancies. These results provide new and direct evidence in support of the idea that specific function can be imparted to specific active sites by tuning their coordination environments, which makes it possible to tailor the catalytic properties of metal oxides to a particular reaction such as propane dehydrogenation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Substitution of transition metals for Cr increases the acidity of the adjacent O. • Linear scaling relations are established to identify the PDH activity descriptor. • High propylene selectivity of the M 1 -Cr 2 O 3 catalysts is achieved. • Cu 1 -Cr 2 O 3 is predicted to be the best catalyst for PDH among the 13 doped Cr 2 O 3. The catalytic behavior of M 1 -Cr 2 O 3 (M = Mn-Cu, Ru-Ag, and Os-Au) in propane dehydrogenation (PDH) has been studied by employing microkinetic modeling combined with results from periodic DFT + U calculations. Calculated results indicate that most of the single atoms concerned can be stably present on the Cr 2 O 3 surface. The adsorption energy calculations and Bader charge analysis demonstrate that the acidity of the O sites adjacent to the M sites would be enhanced upon doping, which in turn strengthens the atomic H adsorption and the co-adsorption of various PDH species. The surface H formation energy is identified as the reactivity descriptor for PDH over the M 1 -Cr 2 O 3 catalysts, and a volcano curve of the PDH activity is obtained. By calculating the difference between the propylene dehydrogenation and desorption barriers, it is found that some M 1 -Cr 2 O 3 catalysts show improved selectivity towards propylene, as compared to Cr 2 O 3. Comparison between the formation barriers of H 2 and H 2 O reveals that single-atom doping has no apparent negative effect on the catalytic stability of the Cr 2 O 3 surface. The Cu 1 -Cr 2 O 3 catalyst is finally identified as the most promising catalyst for PDH among the 13 M 1 -Cr 2 O 3 catalyst candidates, considering the catalytic activity, selectivity, stability, and cost. [ABSTRACT FROM AUTHOR]