Methanol Steam Reforming over Indium-Promoted Pt/Al₂O₃Catalyst: Nature of the Active Surface

Abstract

The surface state of the Pt/In 2 O 3 /Al 2 O 3 catalyst coated onto a microchannel stainless steel reactor was investigated under working conditions using synchrotron-based ambient pressure photoelectron (APPES) and X-ray absorption near-edge structure (XANES) spectroscopies, combined with online mass spectrometry. The surface of the fresh catalyst consists of metallic Pt, In 2 O 3 , and Al 2 O 3 . Reduction under 0.2 mbar of H 2 at 250 °C leads to surface enhancement of Pt and partial reduction of In 2 O 3 , while Al 2 O 3 remains unchanged. Reoxidation in O 2 atmosphere stimulates surface segregation of In 2 O 3 over Pt, accompanied by partial oxidation of Pt to PtO x . Based on these results a dynamic, gas-phasedependent surface state is demonstrated. Under methanol steam reforming conditions, the surface state rapidly adapts under the reaction stream regardless of the pretreatment. However, correlation of gas phase with spectroscopic results under working conditions pointed out the beneficial effect of surface indium to reduce the CO selectivity. Finally, evidence of a distorted symmetry of Al sites on Pt/In 2 O 3 /Al 2 O 3 catalyst compared to that of γ-Al 2 O 3 is given. The findings obtained in the present study are of fundamental significance in understanding the relation between the surface state and the catalytic performance of a functional methanol reforming catalyst.

Ambient Pressure Photoelectron Spectroscopy: Opportunities in Catalysis from Solids to Liquids and Introducing Time Resolution

“…Rameshan et al [104] GaPd 2 Mayr et al [105] ,H aghofer et al [106] In-Pt/Al 2 O 3 Barbosa et al [107] Methaned ry reforming Metal(Co, Ni, Cu)/CeO 2 Liu et al [108] Ethane, butaned ry reforming PtNi/CeO 2 Yanet al [109]…”

Investigation of the Inhibiting Role of Hydrogen in the Steam Reforming of Methanol

“…The reaction products were analyzed by mass spectrometer, using multiple ion detection mode. The intensity of selected ions was monitored (including the ions with m/z = 2, 14,15,16,18,28,29,30,31,32,44,45,60).…”

“…Relevant experimental studies have been also performed for noble metal catalysts, mainly palladium and platinum supported on zinc, indium and gallium oxides. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] Unlike methanol synthesis, which is also carried out on similar catalysts and temperatures, SRM process is not limited by thermodynamic constraints at low temperatures. Thermodynamic restrictions play a lesser role in SRM, as the inverse of methanol synthesis, steam reforming and decomposition reactions can be considered irreversible at atmospheric pressure.…”

Formation and Functioning of Bimetallic Nanocatalysts: The Power of X‐ray Probes

“…Beyond model redox cycling,V irnovskaia et al [72] found with AP-XPS that the surface of Pt-Sn nanocatalysts is Snenriched during high-temperature alkane dehydrogenation and Sn remains partially oxidized even in ah ighly reducing hydrocarbon environment. Barbosa et al [73] showed by AP-XPS during methanol steam reforming that the surface of Pt-In NPs is In-enriched, suppressing CO formation during reaction. During NP sintering,the number of active sites decreases by NP growth.…”