Combined in situ analysis of Ni₂P/MCM-41 under hydrodesulfurization conditions – Simultaneous observation of QXAFS and FTIR –

Operando QEXAFS studies of Ni2P during thiophene hydrodesulfurization: direct observation of Ni—S bond formation under reaction conditions

“…the formation of Ni-S bonds. Combining the previous results of simultaneous XANES and products analysis (Bando et al, 2009(Bando et al, , 2012, the present paper demonstrates that the assumption that the XANES change is due to Ni-S formation is valid. Hence the Ni-S bond at 0.230 nm is involved in the active phase.…”

“…This feature decreased by 10% under steady-state conditions as shown by the dotted line. This small change was reproducible and could be used to follow changes in reaction by monitoring the intensity change in the XANES region as in previous work (Oyama et al, 2009;Bando et al, 2009Bando et al, , 2012. Fig.…”

“…Note that ðk; tÞ has a time dependence while 1 ðkÞ, 2 ðkÞ, 3 ðkÞ are independent of time. Our previous work (Oyama et al, 2004;Kawai et al, 2006Kawai et al, , 2008Bando et al, 2009) indicated that Ni-S bond formation occurs with the Ni 2 P framework unchanged so that c 1 (t) is set constant and (1) can be reduced to…”

“…In order to better elucidate the relationship between the Ni-S bond and the reaction mechanism, time-resolved XAFS studies together with transient product analysis can be a powerful combination. In the past we have carried out such measurements with in situ simultaneous time-resolved XANES measurements of the supported Ni 2 P, focusing on the changes in the XANES signal, together with in situ Fourier transform infrared spectroscopy (FTIR) as well as product analysis (Bando et al, 2009;Oyama et al, 2009). We found that Ni-S bond formation occurred before high activity was observed for the HDS reaction.…”

T-REX: new software for advanced QEXAFS data analysis

“…Invaluable scientific opportunities are the result, as structural and electronic changes during various processes in physics (Frahm et al, 1992;Schroer et al, 2003;Lü tzenkirchen-Hecht & Frahm, 2006), chemistry (Briois et al, 2005;Okumura et al, 2008;Fujimori et al, 2009;Bauer et al, 2010) and biology (Ascone et al, 2003;Haumann et al, 2005) can be studied. It is thus not surprising that QEXAFS becomes more and more a standard tool in materials science, especially in the context of catalysis research (Clausen et al, 1998;Grunwaldt et al, 2001;Dent, 2002;Bando et al, 2009;Silversmit et al, 2009;Reimann et al, 2011;Fö ttinger et al, 2011;Rochet et al, 2011). Apart from QEXAFS it is also possible to measure time-resolved EXAFS in energy-dispersive mode by using bent crystals in combination with an array of photodiodes behind the sample (Matsushita & Kaminaga, 1980;Hagelstein et al, 1989;Dent, 2002;Newton et al, 2007), eventually in combination with a slit moving through the generated polychromatic beam fan in front of the sample (Turbo-XAS) resulting in a sequential QEXAFS-like measurement (Pascarelli et al, 1999).…”