The Role of Support in Formic Acid Decomposition on Gold Catalysts

Formic acid (FA) can easily be decomposed, affording molecular hydrogen through a controllable catalytic process, thus attaining great importance as a convenient hydrogen carrier for hydrogen energetics. Supported gold nanoparticles are considered to be among the most promising catalysts for such applications. However, questions remain regarding the influence of the catalyst support on the reaction selectivity. In this study, we have examined the catalytic activity of typical gold catalysts, such as Au/TiO2, Au/SiO2, and Au/Al2O3 in decomposition of FA, and then compared it with the catalytic activity of corresponding supports. The performance of each catalyst and support was evaluated using a gas-flow packed-bed reactor. It is shown that the target reaction, FA → H2 + CO2, is provided by the presence of gold nanoparticles, whereas the concurrent, undesirable pathway, such as FA → H2O + CO, results exclusively from the acid-base behavior of supports.

Download Full-text

Gas-liquid flows through porous media in microgravity: Packed Bed Reactor Experiment-2

10.22541/au.163693261.16884082/v1 ◽

2021 ◽

Author(s):

Brian Motil ◽

Mahsa Taghavi ◽

Vemuri Balakotaiah ◽

Henry Nahra

Keyword(s):

Gas Flow ◽

Liquid Velocity ◽

Space Station ◽

Particle Diameter ◽

Packed Bed ◽

Packed Bed Reactor ◽

Flow Rates ◽

Test Conditions ◽

Superficial Gas Velocity ◽

Liquid Flows

Experimental results on pressure drop and gas hold-up for gas-liquid flow through packed beds obtained from a second flight on the International Space Station are presented and analyzed. It is found that the gas hold-up is a function of the bed history at low liquid and gas flow rates whereas higher gas hold-up and pressure gradients are observed for the test conditions following a liquid only pre-flow compared to the test conditions following a gas only pre-flow period. Over the range of flow rates tested, the capillary force is the dominant contributor to the pressure gradient and is found to be linear with the superficial liquid velocity but is a much weaker function of the superficial gas velocity. The capillary contribution is also a function of the particle size and varies approximately inversely with the particle diameter within the range of the test conditions.

Download Full-text

Heat and Mass Transfer during Lignocellulosic Biomass Torrefaction: Contributions from the Major Components—Cellulose, Hemicellulose, and Lignin

Processes ◽

10.3390/pr8080959 ◽

2020 ◽

Vol 8 (8) ◽

pp. 959

Author(s):

Ken-ichiro Tanoue ◽

Kentaro Hikasa ◽

Yuuki Hamaoka ◽

Akihiro Yoshinaga ◽

Tatsuo Nishimura ◽

...

Keyword(s):

Gas Flow ◽

Model Simulation ◽

Packed Bed ◽

Douglas Fir ◽

Packed Bed Reactor ◽

Reactor Wall ◽

Measured Temperature ◽

Reactor Performance ◽

Rate Vector ◽

Determining Factor

The torrefaction of three representative types of biomass—bamboo, and Douglas fir and its bark—was carried out in a cylindrical-shaped packed bed reactor under nitrogen flow at 573 K of the reactor wall temperature. As the thermal energy for the torrefaction was supplied from the top and the side of the bed, the propagation of the temperature profile of the bed is a crucial factor for discussing and improving the torrefaction reactor performance. Therefore, the temperature and gas flow rate (vector) profiles throughout the bed were calculated by model simulation so as to scrutinize this point. The measured temperature at a certain representative location (z = 30 mm and r = 38 mm) of the bed was well reproduced by the simulation. The volume faction of the bed at temperatures higher than 500 K at 75 min was 0.89, 0.85, and 0.99 for bamboo, and Douglas fir and its bark, respectively. It was found that the effective thermal conductivity is the determining factor for this difference. The heat of the reactions was found to be insignificant.

Download Full-text

Catalytic Hydrodechlorination of Chlorophenols in a Continuous Flow Pd/CNT-Ni Foam Micro Reactor Using Formic Acid as a Hydrogen Source

Catalysts ◽

10.3390/catal9010077 ◽

2019 ◽

Vol 9 (1) ◽

pp. 77 ◽

Cited By ~ 3

Author(s):

Jun Xiong ◽

Ying Ma

Keyword(s):

Catalytic Activity ◽

Formic Acid ◽

Continuous Flow ◽

Catalyst Surface ◽

Reactor System ◽

Packed Bed Reactor ◽

Pd Catalyst ◽

Ni Foam ◽

Catalytic Hydrodechlorination ◽

Micro Reactor

Catalytic hydrodechlorination (HDC) has been considered as a promising method for the treatment of wastewater containing chlorinated organic pollutants. A continuous flow Pd/carbon nanotube (CNT)-Ni foam micro reactor system was first developed for the rapid and highly efficient HDC with formic acid (FA) as a hydrogen source. This micro reactor system, exhibiting a higher catalytic activity of HDC than the conventional packed bed reactor, reduced the residence time and formic acid consumption significantly. The desired outcomes (dichlorination >99.9%, 4-chlorophenol outlet concentration <0.1 mg/L) can be obtained under a very low FA/substrate molar ratio (5:1) and short reaction cycle (3 min). Field emission scanning electron microcopy (FESEM) and deactivation experiment results indicated that the accumulation of phenol (the main product during the HDC of chlorophenols) on the Pd catalyst surface can be the main factor for the long-term deactivation of the Pd/CNT-Ni foam micro reactor. The catalytic activity deactivation of the micro reactor could be almost completely regenerated by the efficient removal of the absorbed phenol from the Pd catalyst surface.

Download Full-text

Electrooxidation of Methanol on Carbon Supported Gold Nanoparticles

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.313-314.232 ◽

2013 ◽

Vol 313-314 ◽

pp. 232-236

Author(s):

Dan Zhang

Keyword(s):

Gold Nanoparticles ◽

Catalytic Activity ◽

Competitive Adsorption ◽

Chemical Reduction ◽

Reduction Process ◽

Carbon Support ◽

Transmission Electron ◽

Supported Gold Nanoparticles ◽

Supported Gold

Activated carbon supported gold nanoparticles (Au/C) were prepared by a chemical reduction process using NaBH4as a reducing agent. The characterization of transmission electron microscope indicated that the Au nanoparticles (AuNPs) in the Au/C catalyst were highly well dispersed on the carbon support. The catalytic activity of the Au/C catalyst for the methanol electrooxidation (MEO) was investigated by the cyclic voltammetry (CV). The results displayed that the Au/C catalyst exhibited a favorable catalytic activity towards the MEO in alkaline solution. Moreover, the competitive adsorption between OH-and CH3OH on the surface of the AuNPs in the Au/C catalyst existed in the course of the MEO. Based on this competitive adsorption, the mechanism of the MEO on the Au/C catalyst was further investigated.

Download Full-text

Size and Catalytic Activity of Supported Gold Nanoparticles: An in Operando Study during CO Oxidation

The Journal of Physical Chemistry C ◽

10.1021/jp1110554 ◽

2011 ◽

Vol 115 (11) ◽

pp. 4673-4679 ◽

Cited By ~ 104

Author(s):

I. Laoufi ◽

M.-C. Saint-Lager ◽

R. Lazzari ◽

J. Jupille ◽

O. Robach ◽

...

Keyword(s):

Gold Nanoparticles ◽

Catalytic Activity ◽

Co Oxidation ◽

In Operando ◽

Supported Gold Nanoparticles ◽

Supported Gold

Download Full-text

Activity of ceria and ceria-supported gold nanoparticles for the carbamoylation of aliphatic amines by dimethyl carbonate

Pure and Applied Chemistry ◽

10.1351/pac-con-11-06-06 ◽

2011 ◽

Vol 84 (3) ◽

pp. 685-694 ◽

Cited By ~ 7

Author(s):

Raquel Juárez ◽

Avelino Corma ◽

Hermenegildo García

Keyword(s):

Gold Nanoparticles ◽

Catalytic Activity ◽

Aromatic Amines ◽

Au Nanoparticles ◽

Dimethyl Carbonate ◽

Aliphatic Amines ◽

Supported Gold Nanoparticles ◽

Supported Gold

Aliphatic amines react sluggishly with dimethyl carbonate (DMC) to give a mixture of N-methylation and carbamoylation. Nanoparticulated ceria as catalyst increases, in general, conversion and selectivity toward carbamoylation. This increase in catalytic activity and selectivity toward carbamoylation is even increased by deposition of Au nanoparticles on ceria. However, in contrast to aromatic amines for which a complete selectivity toward carbamoylation using ceria-supported Au nanoparticles can be achieved, the catalytic carbamoylation of aliphatic amines by ceria-supported Au nanoparticles occurs only with moderate selectivity.

Download Full-text