Liquid Phase Direct Synthesis of H2O2: Activity and Selectivity of Pd-Dispersed Phase on Acidic Niobia-Silica Supports

ACS Catalysis ◽  
2017 ◽  
Vol 7 (7) ◽  
pp. 4741-4752 ◽  
Author(s):  
Antonella Gervasini ◽  
Paolo Carniti ◽  
Frédérique Desmedt ◽  
Pierre Miquel
Keyword(s):  
Liquid Phase ◽  
Direct Synthesis ◽  
Dispersed Phase ◽  
Silica Supports

Instrumentation for wet steam

2004 ◽  
Vol 218 (8) ◽  
pp. 811-842 ◽  
Author(s):  
A Kleitz ◽  
J M Dorey
Keyword(s):  
Liquid Phase ◽  
Liquid Film ◽  
Direct Determination ◽  
Dispersed Phase ◽  
Wet Steam ◽  
Turbine Performance ◽  
Chemical Measurements ◽  
Formation And Evolution

This paper is devoted to the measuring methods and instrumentation used in the wet-steam area for both aerodynamics measurements (pressure, temperature and velocity) taking into account the interaction between the vapour and the liquid phase, and the characterization of the liquid phase itself (dispersed phase and liquid film). The development of suitable instrumentation is an important part in understanding the formation and evolution of the liquid phase but is now more and more oriented towards practical industrial concerns, such as the direct determination of turbine performance by measuring exhaust wetness or chemical measurements relating to erosion in the transition zone inside the turbine. Emphasis has been given to techniques suitable for use in actual turbines.

Comparative Study of the Optimized Hydrocyclones H13 and HCOT3 for Maximum Liquid Recovery

2017 ◽  
Vol 899 ◽  
pp. 154-159 ◽  
Author(s):  
Fernanda Falqueto Salvador ◽  
Yanne Novais Kyriakidis ◽  
Marcos Antonio de Souza Barrozo ◽  
Luiz Gustavo Martins Vieira
Keyword(s):  
Liquid Phase ◽  
Euler Number ◽  
Industrial Applications ◽  
Maximum Amount ◽  
Dispersed Phase ◽  
Total Efficiency ◽  
Oil Well ◽  
Centrifugal Field ◽  
Well Drilling ◽  
Solid Liquid

In industrial applications, it is very common to use multiple hydrocyclones in parallel to improve the separation. This equipment employs the centrifugal field to promote solid-liquid or liquid-liquid separation. In cases where there is interest in recovering the liquid phase by removing the maximum amount of dispersed phase (waste), such as in oil well drilling units and in water treatment systems, the employment of a hydrocyclone able to promote both the recovering liquid and the concentration of suspension is viable. This paper presents a comparison between two hydrocyclones considered concentrators, called H13 and HCOT3. The results obtained showed that both separators have a satisfactory capacity to concentrate aqueous suspensions, with the underflow-to-throughput ratio equivalent. The Euler number of HCOT3 hydrocyclone was 19% lower than that obtained for the H13 hydrocyclone. Moreover, the results showed that the HCOT3 has a total efficiency of separation 34% greater compared to H13.

scholarly journals Catalytic CO Oxidation and H2O2 Direct Synthesis over Pd and Pt-Impregnated Titania Nanotubes

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 949
Author(s):  
Lucas Warmuth ◽  
Gülperi Nails ◽  
Maria Casapu ◽  
Sheng Wang ◽  
Silke Behrens ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Co Oxidation ◽  
Gas Phase ◽  
Surface Area ◽  
Heterogeneous Catalysts ◽  
Direct Synthesis ◽  
Pt Nanoparticles ◽  
Titania Nanotubes ◽  
Catalytic Co Oxidation ◽  
H2o2 Direct Synthesis

Titania nanotubes (TNTs) impregnated with Pd and Pt nanoparticles are evaluated as heterogeneous catalysts in different conditions in two reactions: catalytic CO oxidation (gas phase, up to 500 °C) and H2O2 direct synthesis (liquid phase, 30 °C). The TNTs are obtained via oxidation of titanium metal and the intermediate layer-type sodium titanate Na2Ti3O7. Thereafter, the titanate layers are exfoliated and show self-rolling to TNTs, which, finally, are impregnated with Pd or Pt nanoparticles at room temperature by using Pd(ac)2 and Pt(ac)2. The resulting crystalline Pd/TNTs and Pt/TNTs are realized with different lengths (long TNTs: 2.0–2.5 µm, short TNTs: 0.23–0.27 µm) and a specific surface area up to 390 m2/g. The deposited Pd and Pt particles are 2–5 nm in diameter. The TNT-derived catalysts show good thermal (up to 500 °C) and chemical stability (in liquid-phase and gas-phase reactions). The catalytic evaluation results in a low CO oxidation light-out temperature of 150 °C for Pt/TNTs (1 wt-%) and promising H2O2 generation with a productivity of 3240 molH2O2 kgPd−1 h−1 (Pd/TNTs, 5 wt-%, 30 °C). Despite their smaller surface area, long TNTs outperform short TNTs with regard to both CO oxidation and H2O2 formation.

scholarly journals Experimental Evaluation of a Membrane Micro Channel Reactor for Liquid Phase Direct Synthesis of Hydrogen Peroxide in Continuous Flow Using Nafion® Membranes for Safe Utilization of Undiluted Reactants

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 556 ◽  
Author(s):  
Manuel Selinsek ◽  
Manfred Kraut ◽  
Roland Dittmeyer
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Phase ◽  
Direct Synthesis ◽  
Product Yield ◽  
Reactor System ◽  
Solid Catalyst ◽  
H2o2 Production ◽  
Reactant Ratio ◽  
Micro Channel ◽  
Micro Channels

In recent years, various modular micro channel reactors have been developed to overcome limitations in challenging chemical reactions. Direct synthesis of hydrogen peroxide from hydrogen and oxygen is a very interesting process in this regard. However, the complex triphasic process (gaseous reactants, reaction in liquid solvent, solid catalyst) still holds challenges regarding safety, selectivity and productivity. The membrane micro reactor system for continuous liquid phase H2O2 direct synthesis was designed to reduce safety issues by separate dosing of the gaseous reactants via a membrane into a liquid-flow channel filled with a catalyst. Productivity is increased by enhanced mass transport, attainable in micro channels and by multiple re-saturation of the liquid with the reactants over the length of the reaction channel. Lastly, selectivity is optimized by controlling the reactant distribution. The influence of crucial technical features of the design, such as micro channel geometry, were studied experimentally in relationship with varying reaction conditions such as residence time, pressure, reactant ratio and solvent flow rate. Successful continuous operation of the reactor at pressures up to 50 bars showed the feasibility of this system. During the experiments, control over the reactant ratio was found to be crucial in order to maximize product yield. Thereby, yields above 80% were achieved. The results obtained are the key elements for future development and optimization of this reactor system, which will hopefully lead to a breakthrough in decentralized H2O2 production.

Direct synthesis of ethylmethoxysilanes by the liquid-phase reaction of silicon, methanol and ethylene

1995 ◽  
Vol 489 (1-2) ◽  
pp. C12-C16 ◽  
Author(s):  
Masaki Okamoto ◽  
Naoto Watanabe ◽  
Eiichi Suzuki ◽  
Yoshio Ono
Keyword(s):  
Liquid Phase ◽  
Direct Synthesis ◽  
Phase Reaction ◽  
Liquid Phase Reaction

ChemInform Abstract: Direct Synthesis of Ethanol Over a Cu-Zn Catalyst in the Liquid Phase.

ChemInform ◽  
1989 ◽  
Vol 20 (20) ◽  
Author(s):  
M. SIMON ◽  
A. MORTREUX ◽  
F. PETIT
Keyword(s):  
Liquid Phase ◽  
Direct Synthesis
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