Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
Incorporating metal nanoparticles into polymer membranes can endow the membranes with additional functions. This work\nexplores the development of catalytic polymer membrane through synthesis of palladium nanoparticles based on the approaches\nof intermatrix synthesis (IMS) inside surface functionalized polyethersulfone (PES) membrane and its application to liquid\nphase reactions. Flat sheet PES membranes have been successfully modified via UV-induced graft polymerization of acrylic\nacid monomer. Palladium nanoparticles have been synthesized by chemical reduction of palladium precursor loaded on surface\nmodified membranes, an approach to the design of membranes modified with nanomaterials. The catalytic performances of the\nnanoparticle incorporated membranes have been evaluated by the liquid phase reduction of ...
The use of hydrogen as an energy vector and raw material for ââ?¬Å?very clean liquid fuelsââ?¬Â\nmanufacturing has been assessed by the catalytic conversion of CO2 to methanol over copper\nbased catalysts. A systematic evaluation of copper based catalysts, prepared varying the chemical\ncomposition, has been carried out at 0.1ââ?¬â??5.0 MPa of total pressure and in the range of 453ââ?¬â??513 K by\nusing a semi-automated LAB-microplant, under CO2/H2 reactant mixture (1/3), fed at GHSV of\n8.8 NLÃ?·kgcat\nâË?â??1Ã?·hâË?â??1. Materialââ?¬â?¢s properties have been investigated by the means of chemical-physical\nstudies. The findings disclose that the addition of structure promoters (i.e., ZrO2/CeO2) strongly\nimproves the textural properties of catalysts, in term of total surface area and exposure of metal\nsurface area (MSA), also reducing the sintering phenomena. The results of the catalytic study clearly\nprove a structure-activity relationship at low reaction pressure (0.1 MPa), while at higher pressure\n(3.0ââ?¬â??5.0 MPa) the reaction path is insensitive to structure and chemical composition....
Hydrogen is considered as a real alternative for improving the current energy scenario in\nthe near future and separation processes are a crucial step for the economy of the process in both\ncentralized and distributed production systems. In this context, Pd-based composite membranes\nappear as an attractive technology trying to reduce the Pd thickness by modifying the commercial\nsupports, mainly formed by metals to fit properly in conventional industrial devices. In most cases,\na final calcination step is required and hence, the metallic support can be oxidized. This work\nanalyzes in detail the properties of intermediate layers generated by in-situ oxidation of tubular PSS\nsupports as a crucial step for the preparation of Pd/PSS membranes. The oxidation temperature\ndetermines the modification of original morphology and permeability by increasing the presence\nof mixed iron-chromium oxides as temperature rises. A compromise solution need to be adopted\nin order to reduce the average pore mouth size and the external roughness, while maintaining\na high permeation capacity. Temperature of 600 ââ??¦C lets to reduce the average pore size from 3.5 to\n2.1 Ã?¼m or from 4.5 to 2.3 Ã?¼m in case of using PSS supports with 0.1 or 0.2 Ã?¼m porous media grades,\nrespectively but maintaining a hydrogen permeation beyond targets of United States of America\nDepartment of Energy (US DOE). Lower temperatures provoke an insufficient surface modification,\nwhile greater values derive in a drastic reduction of permeability. In these conditions, two composite\nmembranes were prepared by ELP-PP, obtaining 14.7 and 18.0 Ã?¼m thick palladium layers in case\nof modifying PSS tubes of 0.1 or 0.2 Ã?¼m media grades, respectively. In both cases, the composite\nPd membranes exhibited a hydrogen perm-selectivity greater than 2000 with permeances ranged\nfrom 2.83 to 5.84Ã?·10âË?â??4 mol mâË?â??2 sâË?â??1 PaâË?â??0.5 and activation energies of around 13ââ?¬â??14 kJ molâË?â??1....
This study investigates treating polyethylene terephthalate (PET) waste water bottles with different mass of ethylene glycol (EG)\nusing reactive extrusion technique at a temperature of 260âË?Ë?C. The study puts emphases on evaluating the thermal, mechanical, and\nchemical characteristics of the treated polyethylene terephthalate.Theproperties of the treatedPET fromthe extruderwere analyzed\nusing FT-IR, TGA, DSC, and nanoindentation.The melt flow indexes (MFI) of both treated and untreated PET were alsomeasured\nand compared. Thermal properties such as melting temperature (...
Computational fluid dynamics (CFD) is coupled with reaction and transport in a micro-scale\npellet simulation to study CO oxidation over Rh/Al2O3 catalyst. The macro-pores are explicitly\nmodeled to study the interaction of these phenomena in both the solid and fluid phases. A catalyst\nlayer is computationally reconstructed using a distribution of alumina particles and a simple force\nmodel. The constructed geometry properties are validated using the existing data in the literature.\nA surface mesh is generated and modified for the geometry using the shrink-wrap method and the\nsurface mesh is used to create a volumetric mesh for the CFD simulation. The local pressure and\nvelocity profiles are studied and it is shown that extreme changes in velocity profile could be observed.\nFurthermore, the reaction and species contours show how fast reaction on the surface of the solid\nphase limits the transport of the reactants from the fluid to meso- and micro-porous solid structures\nand therefore limits the overall efficiency of the porous structure. Finally, the importance of using a\nbi-modal pore structure in the diffusion methods for reaction engineering models is discussed....
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