Lorenzo A. Picos-Corrales

The Effect of Sn Content in a Pt/KIT-6 Catalyst Over its Performance in the Dehydrogenation of Propane

Abstract Propylene is one of the most important commodity chemicals. Its future demand is expected to exceed its production. Alternative routes to obtain this product need to be implemented. Dehydrogenation of propane assisted with catalyst is a promising route to meet demands. The Pt and Cr supported catalysts are amongst the most effective possibilities. However, Pt catalysts are preferred over Cr due to the toxic nature of Cr species. Despite the high performance of the Pt catalysts, they deactivate during reaction, mainly due to coke deposits blocking the active site and/or pores. This effect can be reduced with a support having high connectivity and surface area, like KIT-6. In this work the mesoporous silica KIT-6 was employed as support in a series of Pt-Sn catalysts. The influence of adding or increasing the weight % of Sn to Pt catalyst was studied. There were species of SnO2 and metallic Pt in the fresh catalysts. After reaction, it was found that in the catalysts with the lowest wt % of Sn (0.5), there were metallic Pt and a Pt-Sn alloy. In the rest of the used catalysts (containing 1.0, 1.5 and 2.0 wt % of Sn) the only detected specie was the Pt-Sn alloy. In the two most active catalysts (having 0.5 and 1.5 wt % of Sn), it was observed a difference of three times the quantity of coke deposited on the surface. The catalysts containing the highest coke deposits maintained its activity due to the high connectivity of the support.

Synthesis of quinazolin-4(3H)-ones, an update (microreview)

This microreview covers the newest methods for the synthesis of quinazolin-4(3H)-ones published between 2017 and 2018. The synthetic methods primarily involve the use of a metal catalyst. However, few metal-free synthetic pathways are also addressed.

Open image in new window Synthetic approaches involving cyclic acetal groups for the design of biodegradable and biocompatible polymers (microreview)

This microreview addresses relevant data of current studies involving the exploitation of cyclic acetals in the design of degradable synthetic polymers. Two approaches are presented: polymerization of cyclic acetal units and formation of cyclic acetal units after the polymerization. This microreview contains data from the few fundamental references and literature published in the period from 2007 to 2018.

Microwave-assisted synthesis of benzoxazinediones under solvent-free conditions

ABSTRACT Benzoxazinediones exhibit potential as versatile synthons in the synthesis of wide variety of heterocyclic compounds with biological activity. In this work, an efficient and eco-friendly one-step synthesis of benzoxazine-2,4-diones from phthalic anhydrides derivatives and trimethylsilyl azide using the microwave technique was developed and compared with conventional heating. Microwave irradiation plays a critical role in driving the reaction and providing access to products and/or regioisomers not available from conventional heating. Thus, the regioselectivity of the reaction may be modulated by the irradiation time. Depending on the method employed the benzoxazinediones were isolated with yields in the range of 30–90%. GRAPHICAL ABSTRACT