Catalyst cobalt/molybdenum

The conversion of CO to CO2 can be conducted in two different ways. In the first, gases leaving the gas scmbber are heated to 260°C and passed over a cobalt—molybdenum catalyst. These catalysts typically contain 3—4% cobalt(II) oxide [1307-96-6] CoO 13—15% molybdenum oxide [1313-27-5] MoO and 76—80% alumina, JSifDy and are offered as 3-mm extmsions, SV about 1000 h . On these catalysts any COS and CS2 are converted to H2S. Operating temperatures are 260—450°C. The gases leaving this shift converter are then scmbbed with a solvent as in the desulfurization step. After the first removal of the acid gases, a second shift step reduces the CO content in the gas to 0.25—0.4%, on a dry gas basis. The catalyst for this step is usually Cu—Zn, which may be protected by a layer of ZnO. 

The virgin naphtha feed after having been hydrofined over a cobalt molybdenum catalyst to remove sulftir compounds passes through the Powerformer. After stabilization, the aromatics are recovered by extracdon with... 

Trickle-bed operation is the oldest and the most commonly used its development is described in a recent publication (VI). Cobalt-molybdenum catalysts may be used at a temperature of 360°C and a pressure of 57 atm for the hydrogenation of straight-run gas oils. 

Gas-liquid fluidization is employed in the H-Oil process developed in the United States (H6). Cobalt-molybdenum catalyst particles of -in. diameter may be used at a reaction pressure of 100 atm or more and a temperature of about 400°C (V4). 

Minaev, V. Z. Zaidman, N. M. Spirina, G. A., et al., Effect of Pore Structure of Alumina-Cobalt-Molybdenum Catalyst on Activity and Stability in Hydrodesulfurization of Heavy Feedstocks. Chemistry and Technology of Fuels and Oils, 1975. 11(6) pp. 436-39. 

BASF/Scholven A pretreatment process for benzole, the product formed by hydrogenating hard coal. The benzole is hydrogenated at 300 to 400°C using a molybdenum or cobalt/molybdenum catalyst. The product is a mixture of aromatic hydrocarbons, suitable for separation by a variety of physical processes. The process was invented by BASF in 1925 and adopted by Scholven-Chemie in 1950. Eleven plants in France and Germany subsequently adopted the process. 

Synthoil A coal liquifaction process in which coal, suspended in oil from the process, is hydrogenated over a cobalt/molybdenum catalyst on alumina. The process was piloted by the Pittsburgh Energy Research Center at Bruceton, PA in the 1970s using several types of coal, but it was abandoned in 1978. See also CSF, H-Coal. 

Triolefin A process for disproportionating propylene into a mixture of ethylene and 2-butene. The reaction takes place at 160°C over a cobalt/molybdenum catalyst on an alumina base. Developed by the Phillips Petroleum Company from 1963. A commercial plant was built by Gulf Oil Canada in 1966 and operated by Shawinigan between 1966 and 1972 before closing for economic reasons. 

Mossbauer spectroscopy is one of the techniques that is relatively little used in catalysis. Nevertheless, it has yielded very useful information on a number of important catalysts, such as the iron catalyst for Fischer-Tropsch and ammonia synthesis, and the cobalt-molybdenum catalyst for hydrodesulfurization reactions. The technique is limited to those elements that exhibit the Mossbauer effect. Iron, tin, iridium, ruthenium, antimony, platinum and gold are the ones relevant for catalysis. Through the Mossbauer effect in iron, one can also obtain information on the state of cobalt. Mossbauer spectroscopy provides valuable information on oxidation states, magnetic fields, lattice symmetry and lattice vibrations. Several books on Mossbauer spectroscopy [1-3] and reviews on the application of the technique on catalysts [4—8] are available. 

We begin with the structure of a noble metal catalyst. The emphasis is on the preparation of rhodium on aluminum oxide and the nature of the metal-support interaction. Next we focus on a promoted surface in a review of potassium on noble metals. This section illustrates how single crystal techniques have been applied to investigate to what extent promoters perturb the surface of a catalyst. The third study deals with the sulfidic cobalt-molybdenum catalysts used in hydrotreating reactions. Here we are concerned with the composition and structure of the catalytically active... 

Cobalt-molybdenum catalysts are in general much more active for HDS than single molybdenum catalysts. Thus, it is essential to investigate the state of cobalt in the sulfided Co-Mo/Al203 catalyst. 

Several groups [64-67,76] have reported EXAFS studies on sulfided cobalt-molybdenum catalysts. Figure 9.22 shows the Fourier transforms of M0S2 and of sulfided molybdenum and cobalt-molybdenum catalysts supported on carbon,... 

Figure 14.2 shows that the production of 99% pure hydrogen requires many catalytic processes. The desulfurization section is used to reduce the sulfur content of the natural gas to 0.01 ppm to protect the SMR and WGS catalysts downstream. A supported cobalt-molybdenum catalyst (CoMoS) converts the sulfur compounds into H2S, which is removed by a ZnO catalyst [5]. 

In the SCOT process, the sulfur compounds in the Claus tail gas are converted to hydrogen sulfide by heating and passing it through a cobalt-molybdenum catalyst with the addition of a reducing gas. The gas is then cooled and contacted with a solution of diisopropanolamine (DIPA) that removes all but trace amounts of hydrogen sulfide. The sulfide-rich diisopropanolamine is sent to a stripper, where hydrogen sulfide gas is removed and sent to the Claus plant. The diisopropanolamine is returned to the absorption column. 

Natural gas feedstock is very dependent of the source location in some cases it has high levels of H2S, CO2 and hydrocarbons. Organic sulfur compounds must be removed because they will irreversibly deactivate both reforming and WGS catalysts. Hence a preliminary feed desulfurization step is necessary. This process consists in a medium-pressure hydrogenation (usually on a cobalt-molybdenum catalyst at 290-370 °C), which reduces sulfur compounds to H2S, followed by H2S separation through ZnO adsorption (at 340-390 °C) or amine absorption [9]. 

T-606 Specially compounded refractory oxide support G-39 A cobalt-molybdenum catalyst, used for simultaneous hydrodesulfurization of sulfur compounds and hydrogenation of olefins... 

Activity of carbon-supported cobalt-molybdenum catalysts. 

In order to achieve the goal of reducing sulfur levels in fuels, there is a clear need for understanding the mechanism of the reaction (Chapter 4) in conjunction with the nature of the catalyst and support. Most of the work has been carried out with the traditional cobalt-molybdenum catalyst supported on alumina. This system is a time-tested and effective. 

Two important commercial diacids are adipic acid (hexanedioic acid) and tere-phthalic acid (benzene-1,4-dicarboxylic acid). Adipic acid is used in making nylon 66, and terephthalic acid is used to make polyesters. The industrial synthesis of adipic acid uses benzene as the starting material. Benzene is hydrogenated to cyclohexane, whose oxidation (using a cobalt/acetic acid catalyst) gives adipic acid. Terephthalic acid is produced by the direct oxidation of para-xylene in acetic acid using a cobalt-molybdenum catalyst. 

Relative Volume HDS Activity At Compared to tha Fresh Cobalt/Molybdenum Catalyst. 

---