The SZO used for this study was partially dehydroxylated at 300 o C (SZO300). SZO300 contains 2.3% sulfate (0.72 mmol g -1 ) from ICP-OES analysis and has 74 m 2 g -1 with a moderate loading of Brønsted sites (0.13 ± 0.01 mmol g -1 ). These loadings translate to ~1.1 Brønsted sites nm -2 and ~6 S-containing anions per nm 2 . The FTIR of SZO300 contains a nS=O at 1410 cm -1 , consistent with pyrosulfate formation (Figure ). Reactivity of SZO300 with probes that gauge Lewis acidity are shown in Figure . These studies complement previous work using triethylphosphineoxide (TEPO) or 15 N-pyridine 17 adsorbed onto SZO, and both probes are consistent with the presence of strong Lewis sites on SZO300. ). The numbers under the peaks in the bottom spectrum are integrals for each respective signal. For both experiments nrot = 10 kHz. Spinning side bands marked with a "*". The bottom spectrum was acquired with a 15 s delay between scans.