scholarly journals Improved CO-PROX Performance of CuO/CeO2 Catalysts by Using Nanometric Ceria as Support

Catalysts ◽  
2018 ◽  
Vol 8 (5) ◽  
pp. 209 ◽  
Author(s):  
Almerinda Di Benedetto ◽  
Gianluca Landi ◽  
Luciana Lisi
Keyword(s):  
High Activity ◽  
Catalytic Performance ◽  
Oxidation Of Co ◽  
High Concentration ◽  
Reaction Conditions ◽  
Wet Impregnation ◽  
Preferential Oxidation Of Co ◽  
Icp Ms ◽  
Copper Sites ◽  
Temperature Programmed

Despite of the huge number of papers about the catalytic preferential oxidation of CO (CO-PROX) for the purification of H2 streams, there is still a need for more effective catalysts in order to reduce the large required catalyst volume of CO-PROX unity. In this work, large surface area nanometric ceria was used as support for CuO/CeO2 catalysts with CuO load up to 10 wt % easily dispersed by wet impregnation. Catalysts were characterized by ICP-MS, XRD, SEM/EDS, N2 physisorption, H2 temperature programmed reduction (TPR), and CO2 temperature programmed desorption (TPD) and tested under different reaction conditions (including under feed containing inhibiting species such as CO2 and H2O). Catalytic tests revealed that our samples show high activity and selectivity even under stringent reaction conditions; moreover, they result among the most active catalysts when compared to those reported in the scientific literature. The high activity can be related to the enhanced amount of highly dispersed copper sites in strong interaction with ceria related to the nature of the nanometric support, as evidenced by the characterization techniques. Despite the high concentration of active copper sites, catalytic performance is limited by CO2 desorption from ceria in the neighborhood of copper sites, which prevents a further improvement. This suggests that new catalyst formulations should also provide a lower affinity towards CO2.

scholarly journals Inverse single-site Fe1(OH)X/Pt(111) model catalyst for preferential oxidation of CO in H2

Nano Research ◽  
2021 ◽  
Author(s):  
Chunlei Wang ◽  
Heloise Tissot ◽  
Markus Soldemo ◽  
Junling Lu ◽  
Jonas Weissenrieder
Keyword(s):  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Redox Properties ◽  
Model Catalyst ◽  
Single Site ◽  
Oxide Nanoparticles ◽  
Preferential Oxidation ◽  
Oxidation Of Co ◽  
Reaction Conditions ◽  
Preferential Oxidation Of Co

AbstractInverse oxide/metal model systems are frequently used to investigate catalytic structure-function relationships at an atomic level. By means of a novel atomic layer deposition process, growth of single-site Fe1Ox on a Pt(111) single crystal surface was achieved, as confirmed by scanning tunneling microscopy (STM). The redox properties of the catalyst were characterized by synchrotron radiation based ambient pressure X-ray photoelectron spectroscopy (AP-XPS). After calcination treatment at 373 K in 1 mbar O2 the chemical state of the catalyst was determined as Fe3+. Reduction in 1 mbar H2 at 373 K demonstrates a facile reduction to Fe2+ and complete hydroxylation at significantly lower temperatures than what has been reported for iron oxide nanoparticles. At reaction conditions relevant for preferential oxidation of CO in H2 (PROX), the catalyst exhibits a Fe3+ state (ferric hydroxide) at 298 K while re-oxidation of iron oxide clusters does not occur under the same condition. CO oxidation proceeds on the single-site Fe1(OH)3 through a mechanism including the loss of hydroxyl groups in the temperature range of 373 to 473 K, but no reaction is observed on iron oxide clusters. The results highlight the high flexibility of the single iron atom catalyst in switching oxidation states, not observed for iron oxide nanoparticles under similar reaction conditions, which may indicate a higher intrinsic activity of such single interfacial sites than the conventional metal-oxide interfaces. In summary, our findings of the redox properties on inverse single-site iron oxide model catalyst may provide new insights into applied Fe-Pt catalysis.

Catalytic performance of K-promoted Rh/USY catalysts in preferential oxidation of CO in rich hydrogen

2003 ◽  
Vol 250 (2) ◽  
pp. 255-263 ◽  
Author(s):  
Hisanori Tanaka ◽  
Shin-ichi Ito ◽  
Satoshi Kameoka ◽  
Keiichi Tomishige ◽  
Kimio Kunimori
Keyword(s):  
Catalytic Performance ◽  
Preferential Oxidation ◽  
Oxidation Of Co ◽  
Preferential Oxidation Of Co

Friedel-Crafts Alkylation of o-xylene over V2O5 / ZrO2 Catalysts

2012 ◽  
Vol 11 (2) ◽  
pp. 1-16
Author(s):  
Sreejarani K Pillai ◽  
O Gheevarghese ◽  
I V Tleane
Keyword(s):  
Lewis Acidity ◽  
Bet Surface Area ◽  
High Yield ◽  
Impregnation Method ◽  
Lewis Acid Catalysts ◽  
Reaction Conditions ◽  
Cumene Cracking ◽  
Wet Impregnation ◽  
Nmr Techniques ◽  
Temperature Programmed

The present study has undertaken the Friedel-Crafts benzylation of aromatics over the V2O5/ZrO2 catalysts systems. Catalysts with different V2O5 content (0-15wt %) was prepared by wet impregnation method and characterized by XRD, BET surface area, FTIR and 5’V NMR techniques. The surface acidic properties were determined by temperature programmed desorption of NH3, cumene cracking and perylene adsorption. Under the optimized reaction conditions, these catalysts are found to be very effective and considerably more selective than the conventional homogeneous Lewis acid catalysts. The investigation of vanadia systems-catalyzed benzylation of o-xylene with benzyl chloride revealed that the catalytic activity and product selectivity are sensitive to the precise reaction parameters and can be related to the Lewis acidity of the systems. The reaction is found to be very clean and produces the desired monoalkylated product with high yield.

A Novel NiCl2-CuCl2/HMOR Catalyst for Direct Vapor-Phase Carbonylation of Methanol

2013 ◽  
Vol 316-317 ◽  
pp. 983-986 ◽  
Author(s):  
Hai Xia Wang ◽  
Wen Wen Guo ◽  
Ling Jun Zhu
Keyword(s):  
High Activity ◽  
Methyl Iodide ◽  
Vapor Phase ◽  
Methanol Conversion ◽  
Catalytic Performance ◽  
Composite Catalyst ◽  
Reaction Conditions ◽  
Reaction Pressure ◽  
Methanol Carbonylation ◽  
Optimum Reaction

Direct vapor-phase methanol carbonylation, without any methyl iodide in the feed as a promoter, was carried out over NiCl2-CuCl2/HMOR catalysts. The results showed that NiCl2-CuCl2/HMOR catalysts exhibited high activity for methanol carbonylation. The optimum component of the composite catalyst was 5wt% NiCl2 and 15wt% CuCl2. In addition, the effects of reaction pressure and temperature on catalytic performance of 5%NiCl2-15%CuCl2/HMOR catalyst were investigated. It was revealed that methanol conversion of 84.2% and carbonylation selectivity of 73.5% could be obtained under the optimum reaction conditions of P=1.5MPa and T=623K.

Modification of Mesoporous CaZr4(PO4)6 and its Acid Catalytic Performance

2011 ◽  
Vol 396-398 ◽  
pp. 1851-1855
Author(s):  
Tian Si ◽  
Lin Hua Zhu
Keyword(s):  
Surface Acidity ◽  
Sol Gel ◽  
Acid Catalyst ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
Catalyst Sample ◽  
New Type ◽  
Temperature Programmed ◽  
N2 Sorption

A series of new type acid catalyst samples based on mesoporous CaZr4(PO4)6(CZP) belonging to NZP family synthesized by sol-gel method was obtained by Al, La, B incorporation in CZP or by heteropoly acid H3PW12O7•xH2O(HPW) loading on CZP, and their acid catalytic activity and selectivity were investigated by using α-pinene isomerization as a probe reaction. The phase, pore structure and surface acidity of the catalyst samples were characterized by X-ray diffraction (XRD), N2 sorption and NH3 temperature programmed desorption (NH3-TPD) respectively. The results showed that the surface acidity of CZP modified by elements incorporation and HPW loading was improved in a different extent. The conversion of α-pinene at 150 °C reached to 41 % over the catalyst sample noted as Al-CZP-0.15 in which the mole ratio of Al to Zr was 0.15. Under the same reaction conditions, the conversion of α-pinene was above 95 % over the CZP supported with 20-30wt. %HPW.

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