Circulating reactor

Table 131 Water-gas shift rates of Pt/FSM-16 nano structured catalysts, Pt/zeolite, and Au/ zeolite catalysts in a closed circulating reactor at 50 °c541-543... 

To examine how and why the surface ethanol reaction is assisted by the gas-phase ethanol, the following experiments were conducted in a closed circulating reactor. Ethanol vapor was first admitted onto the dioxoniobium monomer catalyst (1), Si0 2Nb(=0)2, to form the niobium ethox-ide (2), Si0 2Nb(=0)(0H)(0C2H5), at 373 K, followed by evacuation, and then the system was maintained at 523 K for 10 min, where no H2 evolution was observed because the niobium ethox-ide (2) was stable up to 600 K in vacuum. After the confirmation of no H2 formation from the preadsorbed ethanol (2), tert-butyl alcohol was introduced to the system at 523 K, which led to a stoichiometric evolution of H2 and CH3CHO. As the fert-butyl alcohol molecule has no extractable a-hydrogen, it is evident that both H2 and CH3CHO were produced from the preadsorbed ethanol by the assistance of the postdosed tert-butyl alcohol. 

The high temperature process, on the other hand, operates at an elevated temperature where the heat of the direct chlorination reaction actually vaporises a portion of the EDC. This reactor is also a natural circulation reactor, with the liquid EDC circulation driven by the vaporising material. 

Reduction and reoxidation rates were also measured by Brueckman et al. [61], who used a static circulation reactor at 220—460°C. The reduction with hydrogen or propene at 460°C proceeds to Mo02 and Bi°. The very fast reoxidation was studied at much lower temperatures. Bi° is reoxidized first. The reduction process is rather complicated for the molybdenum-rich phases (Bi/Mo = 1/1 and 2/3), which appear initially to form a mixture of Mo02 and the 7-phase. Kinetic equations are presented by the authors, but do not seem relevant for catalysis in view of the too severe... 

The investigations were performed in a closed circulation reactor with a volume of 175 cm. The volume of the reactant sample was 0.3 cm. The carrier gas was helium, freed from oxygen with an Alltech Oxy-Trap. The hydrogen used in the measurements was produced by a Matheson 8326 electrolysis apparatus equipped with a Pd diffusion cell. 2-5 mg catalyst samples were used. Details on the experimental procedure were reported earlier (refs. 5,6). 

Decomposition of NzO on a copper oxide catalyst in adiabatic circulating reactor Hugo (46) X ... 

Oxidation of CO on Cu0/A1203 catalyst in adiabatic circulating reactor Eckert et al. (43, 44) X X... 

Runs at 10°C for both CFC-11 and CFC-113 were conducted in the circulating reactor system to examine temperature effects. In both cases, the apparent first-order rate constant declined slightly. The decline was somewhat lower for CFC-113 than for CFC-11, which may even have remained unchanged. A sonochemical approach has the advantage of not requiring any transference of the target molecule from an aqueous phase as would be required in combustion or catalytic oxidation. 

The third item is other ways to increase heat transfer area. They include circulating reactor liquid through an external heat exchanger or autorefrigeration. The dynamics of both of these alternatives will be studied in Chapter 3. As earlier mentioned, for a jacketed reactor, the heat transfer area can be increased by using larger aspect ratios. 

The oxidation of butane (or butylene or mixtures thereof) to maleic anhydride is a successful example of the replacement of a feedstock (in this case benzene) by a more economical one (Table 1, entry 5). Process conditions are similar to the conventional process starting from aromatics or butylene. Catalysts are based on vanadium and phosphorus oxides [11]. The reaction can be performed in multitubular fixed bed or in fluidized bed reactors. To achieve high selectivity the conversion is limited to <20 % in the fixed bed reactor and the concentration of C4 is limited to values below the explosion limit of approx. 2 mol% in the feed of fixed bed reactors. The fluidized-bed reactor can be operated above the explosion limits but the selectivity is lower than for a fixed bed process. The synthesis of maleic anhydride is also an example of the intensive process development that has occurred in recent decades. In the 1990s DuPont developed and introduced a so called cataloreactant concept on a technical scale. In this process hydrocarbons are oxidized by a catalyst in a high oxidation state and the catalyst is reduced in this first reaction step. In a second reaction step the catalyst is reoxidized separately. DuPont s circulating reactor-regenerator principle thus limits total oxidation of feed and products by the absence of gas phase oxygen in the reaction step of hydrocarbon oxidation [12]. 

Ayame and co-workers recently prepared a superacid of chlorinated alumina (199-203). A1203 was chlorinated by heat treatment with Cl2 gas at temperatures above 800°C in a circulation reactor the material was active for isomerization of paraffins such as butane, pentane, and cyclohexane (201). The chlorinated alumina showed a surface acidity due to the Lewis type of Ho - 14.52 (202, 203). 

In Eq. (18.1), sodium hypochlorite is produced by feeding chlorine into a 30% aqueous caustic solution in a circulating reactor/cooler system. To avoid sodium chlorate formation, the reaction temperature is kept below 30°C and NaOH concentration is kept below 1 g/liter. Typical reaction temperature is 5 °C132. 

Description The Spherizone process is Basell s new proprietary gas-loop reactor technology based on a Multi-Zone Circulating Reactor (MZCR) concept. Inside the reactor (1) the growing polymeric granule is continuously recirculating between two interrelated zones, where two distinct and different fluodynamic regimes are realized. 

Spherizone A development of the Spheripol process for making polypropylene. A special zone is established in the continuous circulating reactor in which additional monomer or a comonomer can be introduced in order to make polymers with different properties. The copolymers can be monomodal, bimodal, random, or twin-random. Nine licenses had been issued in 2006. 

Figure 4.22 Bypass of circulating reactor content around external heat exchanger.

Reaction conditions CO/H2 = 20 45 cmHg in closed circulating reactor of 420 cm capacity. 

Reactions of n-hexane (nH) were studied in a closed loop glass circulation reactor [5, 8]. The catalyst (50 mg) was heated in air at 773 K and reduced in situ at 723 K with 500 Torr H2 for 3 h (with a liquid nitrogen trap). After evacuation, reaction mixtures consisting of 10 or 40 Torr n-hexane and 120 Torr hydrogen were introduced and runs between 5 and 50 (in some cases 0.5 and 135) min were carried out between 603 and 693 K. The products were analyzed by a capillary GLC column (50 m by 0.32 mm fused silica, CP Sil 5 coating) on a Packard Twe 437 GC. The range of analysis embraced Cj-Cg hydrocarbons including Cg aromatics. The pairs ethane-ethene and propane-propene could not be separated properly. Selectivities were calculated on the basis of effluent composition. 

X 10 moles trypsin per liter fluid volume. To demonstrate the feasibility of using the Ford method to determine the active-site of our immobilized enzyme systems, trypsin CVB-PHEMA-PABS-carbamate was treated in a circulation reactor with NPGB and the titration is Illustrated in Figure 4. The amount of p-nitro-phenol produced by the burst is equal to the amount of the active immobilized trypsin which, for this particular system, turns out to be 31% of the total bound enzyme. Active-site titrations of soluble trypsin were performed according to Chase and Shaw (16), and the active molecules for free trypsin was found to be 70% of the total protein involved. Consequently, the retention of active molecules for the immobilized enzyme was calculated 45%. The specific activity is 17% (Table III) for the same system so the efficiency of the system, based on the actually available active sites, was 38%. Thus, 62% of the initially active trypsin bound has lost its activity upon binding. 

The development of the Spherizone technology started in 1995 and was subsequently scaled up from pilot plant to commercial size in 2002, when the new multi-zone circulating reactor (MZCR) was installed at Basell s plant in Brindisi, Italy. 

The catalyst is fed continuously to the multi-zone circulating reactor, which is the core of this new technology. This loop reactor consists of two distinct reaction zones, each operating under its own peculiar fluid-dynamic regime. 

Schmidt, C.U., Mei, G., Meier, G., Bertolini, S., Busch, M., Wulkow, M., Schwibach, M., Prem, A., Batschkin,T. and Weickert, G. (2003) Training simulator for PP multizone circulating reactor process. Polymer Reaction Engineering V,... 

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