Synthesis, characterization and catalytic properties of nanocrystaline Y2O3-coated TiO2 in the ethanol dehydration reaction

In the present study, TiO2 nanopowder was partially coated with Y2O3 precursors generated by a sol-gel modified route. The system of nanocoated particles formed an ultra thin structure on the TiO2 surfaces. The modified nanoparticles were characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) analysis, Zeta potential and surface area through N2 fisisorption measurements. Bioethanol dehydration was used as a probe reaction to investigate the modifications on the nanoparticles surface. The process led to the obtainment of nanoparticles with important surface characteristics and catalytic behavior in the bioethanol dehydration reaction, with improved activity and particular selectivity in comparison to their non-coated analogs. The ethylene production was disfavored and selectivity toward acetaldehyde, hydrogen and ethane increased over modified nanoparticles.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de Ouro Preto Departamento de QuímicaUniversidade Estadual Paulista Departamento de Físico-QuímicaUniversidade Federal de São Carlos (UFSCar) Departamento de QuímicaUniversidade Federal de Santa Catarina Departamento de QuímicaUniversidade Federal de Pelotas Departamento de Química Analítica e InorgânicaUniversidade Estadual Paulista Departamento de Físico-Químic

A Branch-and-Bound Algorithm for Array Distributions

An important problem facing parallelizing compilers for distributed memory mimd machines is that of distributing data across processors. This distribution affects the amout of data movements among processors that is required to execute the computations of the input program. This work proposes a branch--and--bound based method to automatically compute a distribution for the arrays of the input program. The method is able to arrange redistributions of data during program execution. To test the proposed method, we have embedded it into an experimental parallelizing compiler for an Intel iPSC=860. Results with this compiler for example like the Livermore Loop Kernels show that the computed data distributions are very good. 1 Introduction Distributed memory mimd computers (DMMs) offer a cost effective performance because they are less expensive to build than shared memory machines and are scalable to a large number of processors. Unfortunately, these machines are not easy to porgram becaus..

Spécifications du module d'aide à la codification des actes (sous-projet 3 - CIREA)

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