Combined Zr and S XANES Analysis on S-ZrO2/MWCNT Solid Acid Catalyst
Changchang Liu1, Trudy Bolin2, Paul Northrup3,Sungchul Lee4,Charles McEnally1, Patrick Kelleher1, Lisa Pfefferle1, Gary L. Haller1*
1Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06520-8682, USA
2Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA
3Geosciences Department, Stony Brook University
4Energy Laboratory, Corporate R&D Center, Samsung SDI Co., Ltd., 428-5, Gongse-dong, Giheung-gu, Yongin-si, Gyeonggi-do446-577, Republic of Korea
*To whom correspondence should be addressed. E-mail:
Supplementary Materials
When using 30 wt% ZrO2/MWCNT instead of 15wt% ZrO2/MWCNT as the base composite on which (NH4)2SO4 is impregnated with the same S/Zr molar ratio, the S XANES spectra look exactly the same, as shown in Figure S1. We also reproduced the S XANES, first-derivative analysis on the S-ZrO2/MWCNT synthesized using (NH4)2SO4 (Figure S2) and H2SO4 (Figure S3) as precursors. While the results of (NH4)2SO4impregnation are essentially reproducible, the results of H2SO4 impregnation show some discrepancy in the H2SO4/ZrO2/MWCNT first-derivative analysis. Yet it is still different from the spectrum of (NH4)2SO4/ZrO2/MWCNT. The hypothesis that the second sulfate species having to do with zirconia has a proton associated with it therefore needs more supporting evidence.
(a) / (c)(b) / (d)
Figure S1. Comparison of S XANES and first-derivatives of S-ZrO2/MWCNT composites based on 15wt% ZrO2/MWCNT (a and b) and 30wt% ZrO2/MWCNT (c and d).
(a) / (c)(b) / (d)
Figure S2. S XANES and first-derivatives of S-ZrO2/MWCNT composites based on 15wt% ZrO2/MWCNT using (NH4)2SO4 as precursor (a and b same as in text). Reproduced samples and data are shown in (c) and (d).
(a) / (c)(b) / (d)
Figure S3. S XANES and first-derivatives of S-ZrO2/MWCNT composites based on 15wt% ZrO2/MWCNT using H2SO4 as precursor (a and b same as in the text). Reproduced samples and data are shown in (c) and (d).
To test the consistency of using the combined Zr and S XANES method to quantify relative S content, we compared the data collected on three different sets of samples, from the same beamline, but different beamtime runs, namely, Figure (a) z924 and z930, Figure (b) z906 and z909, and Figure (c) 9BM03 and 9BM18. Each set of these samples includes a (NH4)2SO4/ZrO2/MWCNT sample using 15 wt% ZrO2/MWCNT as the base material, and a S-ZrO2/MWCNT sample having been annealed at 450°C in He for 2 hr. Assuming that all the sulfate is retained and the S content in all of the (NH4)2SO4/ZrO2/MWCNT samples is 6.7 wt%, the final S loadings are 2.3 wt%, 2.9 wt% and 3.9 wt%, respectively. While this comparison shows some consistency, errors do exist in that the beamline setup is not the same for different beamtime runs and therefore the data themselves may not be completely comparable.
(a) / (b)(c)
Figure S4. Three sets of reproduced data on the before and after annealing S-ZrO2/MWCNT are compared to see the relative intensity of S K-edge peaks to probe the S content. The before annealing samples are assumed to retain all S in the precursor, i.e., 6.7 wt%.