Vanadium catalysts reactor design

In industrial practice, the laboratory equipment used in chemical synthesis can influence reaction selection. As issues relating to kinetics, mass transfer, heat transfer, and thermodynamics are addressed, reactor design evolves to commercially viable equipment. Often, more than one type of reactor may be suitable for a given reaction. For example, in the partial oxidation of butane to maleic anhydride over a vanadium pyrophosphate catalyst, heat-transfer considerations dictate reactor selection and choices may include fluidized beds or multitubular reactors. Both types of reactors have been commercialized. Often, experience with a particular type of reactor within the organization can play an important part in selection. 

Independently of the work on the chemical composition of sulphuric acid catalysts, attempts to develop kinetic equations to describe the rate of reaction both for mechanistic analysis and reactor design purposes have been numerous. There is much evidence to suggest that in common with its catalytically oxidative behaviour in other environments, valency states of vanadium of V " and V " are involved. Mars and Maessen in 1964 developed a rate expression based on a simple two-step redox mechanism ... 

BASF Platinized asbestos produced by impregnating asbestos with platinic chloride solution followed by reduction with formaldehyde. Operated up to 10-12 years in several 10 20 cm layers. Contained 8-10% platinum. Tubular reactors were still designed for vanadium catalysts until 1950s. Agreement with Grillo up to 1898. 

This review is a survey of the applications and properties of supported liquid phase catalysts (SLP). By a supported liquid phase catalyst is meant the distribution of a catalytically active liquid on an inert porous support and the behaviour of such systems raises many interesting questions on catalyst chemistry, mass transfer in catalysts and reactor design. It is noteworthy thou that such systems have been employed in the chemical industry for many decades - indeed for over a century in the Deacon process for obtaining chlorine from hydrogen chloride - and of almost equally respectable antiquity are the vanadium based catalyst systems used for sulfuric acid manufacture but the recognition of SLP catalysts as possessing features of their own is much more recent. 

Amination of i-butanol to diisobutylamine was investigated on vanadium modified granulated Raney nickel catalyst in a fixed bed reactor. The addition of 0.5 wt.% V to Raney nickel improved the yield of amines and the stability of catalyst. Factorial experimental design was used to describe the conversion of alcohol, the yield and the selectivity of secondary amine as a function of strong parameters, i.e. the reaction temperature, space velocity and NHs/i-butanol molar ratio. Diisobutylamine was obtained with 72% yield at 92% conversion and reaction parameters P=13 bar, T=240°C, WHSV=1 g/g h, and molar ratios NH3/iBuOH= 1.7, H2/NH3= 1.9. 

The highest (iBu)2NH yield (72 %) was obtained a conversion level of 92% and at reaction parameters P=13 bar, T=240°C, WHSV=1.0 g/g h, NH3/iBuOH= 1.7, H2/NH3= 1.9. In conclusion, a secondary amine yield above 70 % can be was obtained in fixed bed reactor using vanadium promoted Raney nickel catalyst without recycling unconverted alcohol. In order to describe the conversion of alcohol, as well as the yield and selectivity of diisobutylamine in the function process parameters, experiments were carried out and results were evaluated according to orthogonal factorial design (6,7). 

Design a multitube fixed-bed reactor system to accomplish the reaction of naphthalene (N) with air to produce phthalic anhydride over a catalyst of vanadium pentoxide on silica gel at a temperature of about 610-673 K. 

From about 1950, Shell 205 and similar catalysts based on alkalized iron and chromium oxides were used exclusively for styrene productioa As plant capacities were rapidly expanded, efforts were increased to improve the performance of the catalyst. Higher potash levels were introduced and cement binders were used to increase strength and selectivity. Ethylbenzene conversion, which was still about 30-50% in the 1950 s, was increased to at least 60% by 1960. Better plant designs were developed and reactors with up to three beds were introduced. One of the first higher selectivity catalysts included vanadium pentoxide with the conventional chromium oxide and potash. Improvements often led to different catalysts being used in a single reactor to optimize operation. 

The results of the analysis of spent catalyst samples collected at different reactor positions are exhibited in Figure 8.6. Vanadium tends to deposit in greater proportion at the top of the reactor, whereas carbon is accumulated preferably at the bottom. The descending-type vanadium deposit profile clearly indicates that the front-end of the catalytic bed is catching more metals. This is the reason why commercial reactors use graded catalyst systems, the front-end catalyst being more tolerant to metal deposition in order to protect downstream catalysts designed to accomplish other... 

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