Understanding the catalytic behavior of sulfated metal oxides has been the topic of several research studies in the past few decades. Their apparent super-acidic behavior has been correlated with the molecular structure of the surface sulfate species. Herein, we couple FTIR and Raman spectroscopies to study the molecular structural evolution of surface sulfate species on mixed metal hydroxides as well as calcined oxides. We show that on the surface of hydroxides, monodentate and possibly bidentate species are dominant, while for SnO2-rich samples, clusters of polymeric sulfate species may also be present. After calcination, sulfate species bind strongly on the surface of mixed oxides, and different configurations can be seen with a range of S=O functionalities of varying strength. Through comparison of the catalytic performance of all sulfate oxides in the tert-butylation of phenol, it was found that SnO2-rich samples show high TBA conversion, with monoalkylated phenols as the primary product.

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In the present study, petroleum-free production of alkylated phenols from glycerol was achieved by judicious use of microbial biosynthesis and heterogeneous catalysis with the aim to advance biomass conversion to industrially relevant chemical products. First, metabolically engineered bacterium Escherichia coli was adopted to convert glycerol to phenol. Biophenol was then extracted from the cell culture using select polymeric resins. Desorption of phenol was achieved with tertiary butyl alcohol, which serves also as a reactant in subsequent heterogeneous catalytic reaction. The adopted resins were also compared as catalysts for alkylation of phenol to tert-butyl phenolic products. Interestingly, the resins exhibited different phenol adsorption and catalytic reactivities. The holistic approach developed by this study offers a unique opportunity to synthesize end products directly from glycerol that cannot be achieved in such an efficient manner (i.e., low temperature, low pressure, and high selectivity) by using microbial biosynthesis or heterogeneous catalysis approaches alone.