Hierarchical PtIn/Mg(Al)O Derived from Reconstructed PtIn-hydrotalcite-like Compounds for Highly Efficient Propane Dehydrogenation

Abstract

The challenges facing propane dehydrogenation are to solve the Pt sintering and carbon deposition. This paper provides a new way to disperse and stabilize Pt species and resist carbon deposition. Highly dispersed Pt species were topologically transformed from reconstructed PtIn-hydrotalcite-like precursors in a flower-like hierarchical microstructure. The lattice confinement of reconstructed hydrotalcite-like precursor is in favor of stabilizing the highly dispersed Pt species, and the hierarchical microstructure is an important factor to prolong its lifetime by enhancing tolerance to carbon deposition. In propane dehydrogenation, the propene selectivity decreases in the sequences of catalyst in flower-like > single-plate > block mass with small, flakeys. A propene selectivity of >97% with a conversion of 48% at 600 °C has been achieved over a flower-like PtIn/Mg(Al)O catalyst. Additionally, no visible Pt sintering can even be observed on this catalyst after a reaction time of 190 h. This strategy provides an effective and feasible alternative for the facile preparation of highly dispersed metal catalysts.

Effect of Reduction Atmosphere on Structure and Catalytic Performance of PtIn/Mg(Al)O/ZnO for Propane Dehydrogenation

“…The calcined product PtIn/MAZ was obtained by calcining the corresponding precursor at 550 • C for 4 h with a heating rate of 5 • C min −1 [19,41]. To be consistent with previous research [22], the loading amounts of Pt and In were 0.5 wt % and 1.4 wt %, respectively.…”

“…Combined with the high In 0 /In 3+ molar ratio and the formation of PtIn alloy in the H 2 /N 2 -reduced sample, it can be deduced that the Pt-In synergistic effect, high Pt dispersion and large In 0 content result in good activity and high stability to some degree. The binding energy (BE) value of In 0 presented a slightly decreasing trend in accordance with the order of H2/N2-, C3H8/H2/N2-, CO-and C3H8-reduced samples, signifying the weakening Pt-In interaction and transfer of electrons from metallic In to Pt species [22]. The electron-rich Pt sites are beneficial to hindering the adsorption of alkenes on active sites, consequently decreasing the likelihood of hydrogenolysis and coking [42].…”

Propylene Synthesis: Recent Advances in the Use of Pt-Based Catalysts for Propane Dehydrogenation Reaction

“…The introduction of Sn 4+ cations in the hydroxide layers increases the positive charge of the layers and strength the electrostatic interaction with platinum in the catalyst, thus decreasing the mobility and preventing the formation of large platinum particles. The metal ions of Pt 4+ and In 3+ were introduced into the hydrotalcite layer during the reconstruction process [87]. The resulting ball-flower-like PtIn/Mg(Al)O catalyst, when used in the PDH reaction, showed very good performance in terms of activity, selectivity for propene and durability, as well as excellent resistance to coke deposition and Pt sintering.…”

MgF2-Modified Hydrotalcite-Derived Composites Supported Pt-In Catalysts for Isobutane Direct Dehydrogenation

“…It is well known that Pt is the most effective active metal for dehydrogenation of light alkanes, but it is easy to sinter and has relatively poor stability [5,6]. Some metallic promoters, such as Sn [7][8][9], In [10][11][12][13], Cu [14], Zn [15,16], Ga [17,18], K [19,20], or Ge [21,22], are usually used to enhance the interaction with Pt from the electronic and geometric aspects so as to resist coke deposition, suppress Pt sintering, and improve the catalytic performance. In addition, the non-metallic promoters, involving element B [23], F [24,25], Cl [26], and P [27], are usually applied to adjust the acid sites and promote the dispersion of active sites on the surface of catalysts.…”

“…The support materials can also influence the catalytic performance, and a lot of studies have been conducted on the support materials, such as Al 2 O 3 [9,28,29], MgO [30], SiO 2 [27,31], ZrO 2 [15,23,32], and spinel ZnAl 2 O 4 [7,33,34], for isobutane dehydrogenation catalysts. Now, the focus has been switched to calcined hydrotalcite or hydrotalcitelike (HT) composites, which have been used in direct dehydrogenation of propane and have good performance compared to other supports [10][11][12]. Calcined hydrotalcite or hydrotalcite-like (HT) materials are the typical composite metal oxides [35][36][37].…”