Catalysts qualities

Catalyst quality. The early FCC catalysts were neither very active nor very selective yield structure contained too much coke at the... 

FCC Gasoline. The produced light FCC gasoline typically contains a mixture of paraffins, olefins, and aromatic compounds in a ratio of around 5 3 2. This ratio will often vary depending upon feedstock, catalyst quality, and reactor parameters. The research octane number of FCC gasoline will typically be much higher than the motor octane number. 

Metal catalysts composed of more than two different metal elements are of interest from both technological and scientific viewpoints for improving the catalyst quality or properties (20). In fact, bimetallic (or multimetallic) catalysts have long been valuable for in-depth investigations of the relationship between catalytic activity and catalyst particle structure (21). Sinfelt et al. have made a series of studies on bimetallic nanoparticle catalysts supported on inorganic supports, for example,... 

Catalyst quality on a microscopic length scale (quality, number of active sites)... 

Catalyst quality on a mesoscopic length scale (diffusion length, loading, profiles)... 

Petrochemical processes require smaller reactors than used in refineries. Chemical reactors are sized in the 50 to 250 cu.ft. range. Orders for replacement catalyst usually range from 10,000 to 50,000 lbs, but there are many different process applications. Catalyst quality is becoming more important than in recent years as many industries attempt to reduce the cost of nonconformance and improve the quality of manufactured goods. 

The way out of this situation is to introduce appropriate statistical process control procedures in the manufacturing processes of the supplier, his suppliers, and the user. Through these efforts, satisfactory as well as unsatisfactory performances of individual lots of catalysts can be determined, and lot to lot variations of catalyst quality can be identified. 

Rewards for this course of action are seen in more consistent catalyst quality, eventually reduced analytical costs, and opportunities to develop preferred supplier status to meet the special needs of the customer s individual chemical unit. 

Conventional quality control procedures fall short of current needs to improve the consistency of purchased catalyst quality and are being supplemented by the use of control charts and statistical process control. 

Quantitative information on the reproducibility of tests with diluted catalyst beds in microflow reactors was obtained from a series of tests with a standard catalyst and feedstock carried out in the context of monitoring catalyst quality in commercial catalyst production. From the data listed in Table IX it can be inferred that a good reproducibility can be obtained provided due attention is given to experimental details of the testing procedure such as reactor filling, start up and control of reaction conditions. 

Hydrogen factor. This is a relative number proportional to the specific hydrogen yield, defined as specific H2 = H2 yield (100-conversion)/conversion. The hydrogen factor depends on the catalyst quality and is affected by nickel deposited on an equilibrium... 

Porous ceramic or micrometallic filters are very effective for recovering entrained fines from gas streams (228,252). Multiple installations are required because it is necessary to blow back each filter element periodically to dislodge the catalyst cake that builds up on the surface and leads to increased pressure drop. Filters have been used for catalyst recovery in other fluid-catalyst processes where high cost or other considerations justify extraordinary measures to minimize catalyst losses. However, this expedient has not been employed in commercial fluid cracking units because losses are readily controlled to a reasonable level by simpler means. In fact, intentional discard of catalyst is often practiced, in addition to normal losses, in order to maintain catalyst quality at a high level by permitting increased additions of fresh catalyst. 

Beta zeolite catalyst can be optimized to nearly eliminate all undesirable side reactions in the production of cumene. The improvement in beta zeolite catalyst quality has occurred to the point that any significant impurities in the cumene product are governed largely by trace impurities in the feeds. The selectivity of the catalyst typically reduces by-products to a level resulting in production of ultrahigh cumene product purities up to 99.97 wt%. At this level, the only significant byproduct is n-propylbenzene with the catalyst producing essentially no EB, butylbenzene, or cymene beyond precursors in the feed. Fig. 7 shows the reactions of some common feedstock impurities that produce these cumene impurities. 

Traces of water vapor in the gas stream tend to hydrolyze Cr-O-Si linkages, which tends to destabilize surface Cr(VI) [74,75]. Free Cr03 decomposes at a temperature of about 200 °C. Therefore, the purity of the fluidization gas used during the calcination of the catalyst can be important. Because the catalyst itself evolves moisture as silanol groups condense, the rate of temperature rise can also influence the stability of Cr (VI), because a rapid temperature rise results in a gas stream with a higher water concentration. Similarly, the bed depth during fluidized-bed activation can determine moisture concentrations and therefore control Cr(VI) levels. Much commercial art has developed around these principles to achieve a compromise between catalyst quality and catalyst production rate (Section 20). 

This sequence posed few problems. However, the hydrogenation step was always going to be problematic, for two reasons. First, the catalyst quality and second the propensity of alcohol 58 to cyclize to lactone 61. In order to avoid this, the strategy was twofold fast hydrogenation was... 

In brief, the key issue in high-temperature catalytic combustion is how to develop heat-resistant catalytic materials in particular, retention of large surface area is one of the main indicators used to rank catalyst quality. 

Solvents are recovered by distillation in four rectification and stripping columns with a total recovery capacity of 700 litres per hour and a range of 12-27 theoretical plates. Rhodium is recovered by a process which has been patented, and returned to the original manufacturer for refining and transformation into catalyst quality. Some 80% rhodium is recovered. Triphenyl phosphine is recovered as its oxide and can be reconverted for reuse. 

Second step Parallel preparation and testing of catalyst materials of the first generation and evaluation of catalyst quality. 

V.Yu. Gavrilov, in R.A. Byanov, N.N. Bobrov (Editors), Standardization of methods, apparatusses and devices for the control over commercial catalysts quality, Proc. USSR Symp., Novosibirsk, September 25-27,1991, p. 128 (in Russian). 

Develop a mathematical index (or the equivalent), that defines catalyst quality in terms of temperature, reactant concentration and product formation. 

Up to about 1945 the typical naphthalene oxidation catalyst was fused vanadium pentoxide, sometimes combined with molybdenum trioxide, on an inert support. At that time US production of phthalic anhydride was probably less than 60,000 tonnes year and catalyst quality was not very important. 

Equilibrium catalyst attrition index and average particle size distribution (APS) indicate changes in the rate of catalyst attrition. Further analysis of APS for any catalyst that is carried forward into the fractionator, present in the slurry, or which leaves the unit via the regenerator stack can identify problems associated with catalyst quality or cyclone operation. Problems include operation at greater than design feed, catalyst rates or cyclone maloperation. APS is also important in predicting the fluidization properties of the catalyst inventory. 

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