Development of a reaction cell for in-situ/operando studies of surface of a catalyst under a reaction condition and during catalysis

Abstract

Tracking surface chemistry of a catalyst during catalysis is significant for fundamental understanding of catalytic performance of the catalyst since it allows for establishing an intrinsic correlation between surface chemistry of a catalyst at its working status and its corresponding catalytic performance. Ambient pressure X-ray photoelectron spectroscopy can be used for in-situ studies of surfaces of different materials or devices in a gas. To simulate the gaseous environment of a catalyst in a fixed-bed a flowing gaseous environment of reactants around the catalyst is necessary. Here, we report the development of a new flowing reaction cell for simulating in-situ study of a catalyst surface under a reaction condition in gas of one reactant or during catalysis in a mixture of reactants of a catalytic reaction. The homemade reaction cell is installed in a high vacuum (HV) or ultrahigh vacuum (UHV) environment of a chamber. The flowing gas in the reaction cell is separated from the HV or UHV environment through well sealings at three interfaces between the reaction cell and X-ray window, sample door and aperture of front cone of an energy analyzer. Catalyst in the cell is heated through infrared laser beam introduced through a fiber optics interfaced with the reaction cell through a homemade feedthrough. The highly localized heating on the sample holder and Au-passivated internal surface of the reaction cell effectively minimizes any unwanted reactions potentially catalyzed by the reaction cell. The incorporated laser heating allows a fast heating and a high thermal stability of the sample at a high temperature. With this cell, a catalyst at 800 °C in a flowing gas can be tracked readily.

Integrated In Situ Characterization of a Molten Salt Catalyst Surface: Evidence of Sodium Peroxide and Hydroxyl Radical Formation

“…With regard to the OCM selectivity,t he active site has been extensively discussed for Mn/Na 2 WO 4 /SiO 2 (or supported on other oxides). [1,2,9,11,14] In our previous study, [1d] we confirmed that Mn and Ware not essential components for the selective OCM reaction. However, H 2 Owas identified as ak ey reactant (wet condition).…”

“…Thes urface states of the Na 2 WO 4 /TiO 2 catalyst under different gas atmospheres (O 2 + H 2 Oo rO 2 + CH 4 )a t8 00 8 8C were investigated using the AP-XPS system using af lowing reaction cell built by the Taogroup. [9] Photoemission features of subshell electrons of surface atoms can be collected when the catalyst is heated up to 850 8 8Cinaflowing gas.The Na 1s, O1s, and W4ffeatures of the catalyst in UHV and different gas atmospheres at different temperatures are shown in Figure 3. Theb inding energies of these spectra were calibrated to Au 4f 7/2 of Au foil, which was used to support the Na 2 WO 4 /TiO 2 catalyst particles (Supporting Information, Figure S7).…”

Catalytic Intermediates of CO2 Hydrogenation on Cu(111) Probed by In Operando Near‐Ambient Pressure Technique

“…[23,24] Althoughahigh-pressure cell method( HPCM) can be exploited, there still exists ag ap between the in operando species(at high pressures andtemperatures) and the in situ results (after gas evacuation and cooling, HPCM) because the in operando speciesmay evolve in the evacuation or cooling processes. [11,18,19,27,28] In this work, we reporta ni noperando study under near-ambient pressure to give detailedi nsights into the CO 2 hydrogenation on the Cu(111)s urface by using NAP-XPS. [11,18,19,27,28] In this work, we reporta ni noperando study under near-ambient pressure to give detailedi nsights into the CO 2 hydrogenation on the Cu(111)s urface by using NAP-XPS.…”

Integrated In Situ Characterization of a Molten Salt Catalyst Surface: Evidence of Sodium Peroxide and Hydroxyl Radical Formation

“…The surface states of the Na 2 WO 4 /TiO 2 catalyst under different gas atmospheres (O 2 +H 2 O or O 2 +CH 4 ) at 800 °C were investigated using the AP‐XPS system using a flowing reaction cell built by the Tao group 9. Photoemission features of subshell electrons of surface atoms can be collected when the catalyst is heated up to 850 °C in a flowing gas.…”

“…With regard to the OCM selectivity, the active site has been extensively discussed for Mn/Na 2 WO 4 /SiO 2 (or supported on other oxides) 1, 2, 9, 11, 14. In our previous study,1d we confirmed that Mn and W are not essential components for the selective OCM reaction.…”