Hydrothermal saline promoted grafting of periodic mesoporous organic sulfonic acid silicas for sustainable FAME production

Hydrothermal saline promoted grafting of sulfonic acid groups onto SBA-15 and periodic mesoporous organic silica analogues affords solid acid catalysts with high acid site loadings (>2.5 mmol g-1 H+), ordered mesoporosity and tunable hydrophobicity. The resulting catalysts show excellent activity for fatty acid esterification and tripalmitin transesterification to methyl palmitate, with framework phenyl groups promoting fatty acid methyl esters production. (Chemical Equation Presented

On the influence of Si:Al ratio and hierarchical porosity of FAU zeolites in solid acid catalysed esterification pretreatment of bio-oil

A family of faujasite (FAU) zeolites with different Si:Al ratio, and/or hierarchical porosity introduced via post-synthetic alkaline desilication treatment, have been evaluated as solid acid catalysts for esterification pretreatments of pyrolysis bio-oil components. Acetic acid esterification with aliphatic and aromatic alcohols including methanol, anisyl alcohol, benzyl alcohol, p-cresol and n-butanol was first selected as a model reaction to identify the optimum zeolite properties. Materials were fully characterised using N2 porosimetry, ICP, XRD, XPS, FT-IR, pyridine adsorption, NH3 TPD, In-situ ATR and inverse gas chromatography (IGC). IGC demonstrates that the surface polarity and hence hydrophobicity of FAU decreases with increased Si:Al ratio. Despite possessing a higher acid site loading and acetic acid adsorption capacity, high Al-content FAU possess weaker acidity than more siliceous catalysts. Esterification activity increases with acid strength and decreasing surface polarity following the order FAU30>FAU6>FAU2.6. The introduction of mesoporosity through synthesis of a hierarchical HFAU30 material further enhances esterification activity through improved acid site accessibility and hydrophobicity. Methanol was the most reactive alcohol for esterification, and evaluated with HFAU30 for the pretreatment of a real pyrolysis bio-oil, reducing the acid content by 76% under mild conditions

Catalysing sustainable fuel and chemical synthesis

Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from such combustible carbon, are driving academic and commercial research into new sustainable routes to fuel and chemicals. The quest for such sustainable resources to meet the demands of a rapidly rising global population represents one of this century’s grand challenges. Here, we discuss catalytic solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels, and oxygenated organic molecules for the manufacture of fine and speciality chemicals to meet future societal demands

Combined theoretical and experimental kinetic approach for methane conversion on model supported Pd/La0.7MnO3 NGV catalyst: Sensitivity to inlet gas composition and consequence on the Pd-support interface

New insights into reaction mechanism for catalytic methane combustion are provided in broad operating conditions on Pd/La0.7MnO3 as model natural gas vehicle catalyst. Under lean and dry conditions, a dual mechanism is suggested with active sites combining reactive oxygen species from La0.7MnO3 and palladium instead of single site reaction mechanism. Aging in wet atmosphere has no consequence on the kinetic behavior. On the other hand, in wet atmosphere near the stoichiometry, strong accumulation of hydroxyl groups on the support would suppress the metal-support interface. Accordingly, methane combustion would take place only on Pd particles

Pt metal supported and Pt4+ doped La1−xSrxCoO3: non-performance of Pt4+ and reactivity differences with Pt metal

In the present work, we correlate the CO-oxidation activity with the oxidation state of platinum with combined experimental and DFT calculations. XPS reveals that Pt supported La1−xSrxCoO3 (Pt/La1−xSrxCoO3) and Pt doped La1−xSrxCoO3 (La1−xSrxCo1−yPtyO3) consist of Pt in 0 and + 4 oxidation states respectively. Further, catalytic CO oxidation over Pt-doped and Pt-supported La1−xSrxCoO3 in the presence of oxygen demonstrates the lowest activity of the doped compound. Pt supported La1−xSrxCoO3 showed the highest activity with almost 100% conversion at 150 °C. La1−xSrxCo1−yPtyO3 was slightly inferior to the blank La1−xSrxCoO3 suggesting that Pt4+ is an inactive or non-performing entity in the doped compound. Temperature programmed desorption (TPD) demonstrates the low amount of CO desorption from La1−xSrxCoO3 and Pt-doped La1−xSrxCoO3 due to the very weak interaction. On the other hand, Pt-supported La1−xSrxCoO3 shows a substantial amount of CO desorption due to strong interaction and large number of metallic sites available for adsorption. This was supported by density functional theory (DFT) based calculations which showed that Pt-supported La1−xSrxCoO3 surface has higher binding energy of CO than the La1−xSrxCoO3 surface confirming the strong CO interaction. Transient responses using mass spectrometer suggest that the Pt supported perovskite utilizes the lattice oxygen for the reaction and vacancies are formed which gets filled with gaseous oxygen. No such phenomenon is observed in the doped compound demonstrating the mechanistic differences in the two catalysts. Often, during the synthesis of Pt-based compounds, it is common to get mixed phases of platinum including Pt4+. From this study, it can be established that one can discard the contribution from Pt4+ in the calculations of kinetic data such as rate or turnover number because this oxidation state is inactive/nonperforming.by Anuj Bisht, Amita Sihag, Akkireddy Satyaprasad,Sairam S. Mallajosyala and Sudhanshu Sharm