E F G H. 9th January 2013

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1 A B D ompare with E ompare D with F, G and H E F G H 9th January 03 Supplementary Figure S. omparison of µ-t image slices of the catalyst sample with those derived by XD from application of PDF computed tomography. A & B show orthogonal vertical slices derived by µ-t. The white lines overlaid indicate the positions at which cross sections were measured with XD/PDF-T; the µ-t cross-sections at these positions are shown in and D. High contrast at the periphery indicates deposited material. XD/PDF-T (intensity at Q =.37Å which contains contributions from both γ-alumina and PdO) cross-sections of the sample in partially calcined, calcined and reduced states are shown in E, F & G respectively. A large void in the alumina is visible in A and in cross-section in ; this void matches the position of the void in E. An XD/PDF-T cross-section of the sample in the reduced state showing intensities at Q =.77 Å (which contains contributions from γ-alumina and Pd) is shown in H; this shows that the deposited material visible in the µ- T is chiefly metallic Pd when in the reduced state. Abbreviations: XD (X-ray Diffraction); PDF (Pair Distribution Function); T (omputed Tomography).

2 Supplementary Figure S. Micro-distributions in a cylindrical catalyst extrudate. A schematic description of the micro-distributions of an active phase in a cylindrical extrudate as observed when bisected.

3 The catalyst body sits within a quartz glass tube allowing in situ delivery of gasses. The container can be easily separated from the sample. Supplementary Figure S3. Maps of raw reconstructed intensities at selected Q values. Diffraction intensity maps at Q values corresponding to Bragg (00) and () peaks of PdO and Pd respectively and presented in left and right columns respectively. In these images, there is a contribution to the diffraction from the quartz glass container tube, but this is clearly spatially separated from the catalyst body under study; the -alumina signal has been subtracted for the purposes of this display. Note that these images are presented with a common linear colour scale bar (having arbitrary intensity units).

4 alcined 3 3 Position Position 3 P P Supplementary Figure S4. Plots of selected diffraction patterns. Top left, portions of selected diffraction patterns at three positions, indicated in top right sub-figure, in the reconstructed slice for the sample in calcined state. Bottom left, portions of selected diffraction patterns at position for the sample in the partially calcined, calcined and reduced states labeled P, and respectively. Likewise, the diffraction patterns at position 3 are shown in the subfigure bottom right. Sticks have been overlaid on the diffraction data to indicate the positions and relative intensities of Bragg reflections of the crystalline phases. Green, red and blue sticks correspond to γ-alumina, PdO, and Pd respectively.

5 3 3 r [Ang] Position Position 3 r [Ang] r [Ang] Supplementary Figure S5. Plots of selected PDF transforms. Top left, portions of selected PDF at three positions, indicated in top right sub-figure, in the reconstructed slice for the sample in reduced state; the image is made at r =.7 Å -. Bottom left, portions of selected PDF at position for the sample in the calcined and reduced states labeled and respectively. Likewise, the PDF s at position 3 are shown in the subfigure bottom right. Abbreviations: PDF (Pair Distribution Function).

6 Beam tube BS otation stage Alignment camera Detector BS otation stage Supplementary Figure S6. Annotated photographs of the experimental setup showing aerial and side views. Aerial (left) and side (right). The annotations indicate the positions of various components including two Le Mini heat guns; BS indicates the backstop.