Availability and Cost of the Catalyst

The availability and cost of the catalyst cannot be addressed within the framework of a technological assessment of a process. However, for a logistical assessment of a process not only are the availability (and delivery times) and price of the catalyst very important, but so are questions of proper formulation and storage as well as safety. As mentioned above, a laboratory chemist has no control over the price of a catalyst offered whereas a company desiring to produce a certain product can plan ahead to supply the catalyst at the right time and price. 

Availability and cost of the catalyst chiral ligands and many metal precursors are expensive and/or not easily available. Typical costs for chiral diphosphines are 100 to 500 /g for laboratory quantities and 5,000 to >20,000 /kg on a larger scale (only few ligands are available commercially). Chiral ligands used for early transition metals are usually cheaper. 

Design considerations and costs of the catalyst, hardware, and a fume control system are direcdy proportional to the oven exhaust volume. The size of the catalyst bed often ranges from 1.0 m at 0°C and 101 kPa per 1000 m /min of exhaust, to 2 m for 1000 m /min of exhaust. Catalyst performance at a number of can plant installations has been enhanced by proper maintenance. Annual analytical measurements show reduction of solvent hydrocarbons to be in excess of 90% for 3—6 years, the equivalent of 12,000 to 30,000 operating hours. When propane was the only available fuel, the catalyst cost was recovered by fuel savings (vs thermal incineration prior to the catalyst retrofit) in two to three months. In numerous cases the fuel savings paid for the catalyst in 6 to 12 months. 

As apparatus for the batch process, an enamel or steel reactor with an agitator and pressure steam or oil heating suffices. Apparatuses used in the continuous synthesis in the presence of solvents and in the bake process are described in [50] and [51,52], respectively. The choice of process depends on the availability and cost of the starting materials phthalodinitrile or phthalic anhydride. Although the phthalodinitrile process has certain advantages over the phthalic anhydride process, the latter is preferred worldwide because of the ready accessibility of phthalic anhydride. In this process the molar ratio of phthalic anhydride, urea, and cop-per(i) chloride is 4 16 1, with ammonium molybdate as catalyst. The mixture is heated in a high-boiling solvent such as trichlorobenzene, nitrobenzene, or kerosene. The solvent is removed after the formation of copper phthalocyanine. Fre-... 

Similarly, the reaction of nitro compounds with the M-Boc aromatic imines 86 occurred in the presence of the enantiopure protic catalyst 87, which is a white, crystalline bench-stable salt [52] (Scheme 15). The reactions of ni-tromethane, very slow at - 20 °C, were accelerated in the presence of 10 mol % of 87, and the /3-amino compounds 88 were obtained with moderate yields and moderate to high enantioselectivities. Positive results were also obtained in the corresponding reactions of nitropropane to give the products 90. Hence, the primary diamines 89 and 91 are available by this route, which is advantageous for the significantly lower cost and toxicity of the catalyst and its easy removal from the reaction mixture simply by a basic wash. These results should stimulate further research on the development of new acid-catalyzed systems. 

In principle, any catalyst developed in the laboratory can be manufactured in large scale. In practice, however, the necessary investments, which may include development of the production process, and die operating costs of the catalyst production plant including availability and cost of raw materials, plant maintenance, labour etc. may not be justified by the market potential. In the VK69 case, production in the existing plant according to the route in Fig. 8 was preferred but not a strict requirement. 

For adequate reaction rates, a high concentration of iodide anion is necessary. The cation portion of the salt appears to have little or no effect on catalytic activity or reaction selectivity. Inorganic iodides (such as potassium iodide) are the obvious first choice based on availability and cost. Unfortunately these catalysts have very poor solubility in the reaction mixture without added solubilizers or polar, aprotic solvents. These solubilizers (e.g., crown ethers) and solvents are not compatible with the desired catalyst recovery system using an alkane solvent. Quaternary onium iodides however combine the best properties of solubility and reactivity. 

Catalyst consumption is a major aspect of the hydrodesulfurization process and costs of the process increase markedly with the high-metal feedstocks. The ease with which the catalyst can be replaced depends, to a large extent, on the bed type, and with the high-metal feedstocks it is inevitable that frequent catalyst replacement will occur. From the data available (Table 5-7) (Nelson, 1976), attempts have been made to produce a correlation (Figure 5-10) (Nelson, 1976)... 

The performance indexes, which define an optimal catalyst distribution, include effectiveness, selectivity, yield and deactivation rate. The key parameters, affecting the choice of the optimal catalyst profile, are the reaction kinetics, the transport resistances, and the production cost of the catalyst. An extensive review of the theoretical and experimental developments in this area is available [20]. Two typical examples to demonstrate the importance of an appropriate distribution of the active components are now described. 

It would be desirous to have available a sinq)ler testing tool which could imitate many of the aspects of the cyclic deposition particularly the inq)ingement of the metals on the catalyst surface with the simplicity, efficiency, and cost of the Mitchell Method. One such test, at least so far developed for vanadium interaction, is what we termed above as the Engelhard Transfer Method (ETM) (7). 

The availability and cost of 0-methoxypropionitrile should be considered since it has been produced only on a commercial scale as a chemical intermediate. Acrylonitrile reacts readily with aliphatic alcohols in the presence of strong alkaline catalysts to form a broad spectrum of compounds known as alkoxypropionitriles. These reactions, commonly known as cyanoethylation reactions, have long been of interest to organic chemists because of the ease with which the addition takes place (6). The availability of low cost acrylonitrile and methanol has now given -methoxypropionitrile an attractive price tag. Cost estimates for producing this solvent are in the range of 20 to 25 cents/lb. 

C, 0.356—1.069 m H2/L (2000—6000 fU/bbl) of Hquid feed, and a space velocity (wt feed per wt catalyst) of 1—5 h. Operation of reformers at low pressure, high temperature, and low hydrogen recycle rates favors the kinetics and the thermodynamics for aromatics production and reduces operating costs. However, all three of these factors, which tend to increase coking, increase the deactivation rate of the catalyst therefore, operating conditions are a compromise. More detailed treatment of the catalysis and chemistry of catalytic reforming is available (33—35). Typical reformate compositions are shown in Table 6. 

Base Metal Catalyst - An alternate to a noble metal catalyst is a base metal catalyst. A base metal catalyst can be deposited on a monolithic substrate or is available as a pellet. These pellets are normally extruded and hence are 100% catalyst rather than deposition on a substrate. A benefit of base metal extruded catalyst is that if any poisons are present in the process stream, a deposition of the poisons on the surface of the catalyst occurs. Depending on the type of contaminant, it can frequently be washed away with water. When it is washed, abraded, or atritted, the outer surface is removed and subsequently a new catalyst surface is exposed. Hence, the catalyst can be regenerated. Noble metal catalyst can also be regenerated but the process is more expensive. A noble metal catalyst, depending on the operation, will typically last 30,000 hours. As a rule of thumb, a single shift operation of 40 hours a week, 50 weeks a year results in a total of 2,000 hours per year. Hence, the catalyst might have a 15 year life expectancy. From a cost factor, a typical rule of thumb is that a catalyst might be 10%-15% of the overall capital cost of the equipment. 

The available data in Table 6 reveal that palladium complexes are excellent catalysts for selective hydrogenation of C=C in NBR. Recent attempts to recover the catalyst (see Section VII) after hydrogenation and lower the cost of the metal make it an attractive supplement in the industrial production of HNBR. 

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