Upflow reactor

Propylene feed, fresh benzene feed, and recycle benzene are charged to the upflow reactor, which operates at 3—4 MPa (400—600 psig) and at 200—260°C. The SPA catalyst provides an essentially complete conversion of propylene [115-07-1] on a one-pass basis. A typical reactor effluent yield contains 94.8 wt % cumene and 3.1 wt % diisopropylbenzene [25321-09-9] (DIPB). The remaining 2.1% is primarily heavy aromatics. This high yield of cumene is achieved without transalkylation of DIPB and is unique to the SPA catalyst process. 

Upflow reactor a reactor in which the feedstock flows in an upward direction through the catalyst bed. 

The Livermore study used a 1.8 L upflow reactor, packed with a 1% w/w Pd/alumina catalyst, nominally 0.32 cm in diameter. (McNab and Ruiz 1998) The water supply consisted of groundwater from a well at the Livermore site and contained PCE (5-7 jig/L), TCE (500-600 tig/L), 1,1-DCE (15-25 pg/L), CT (8-15 fig/L), CF (4-10 gg/L), and 1,2-DCA (4-10 jrg/L). The water was first passed through an electrolyzer, which served as a source of hydrogen. With an average residence time of 2.3 minutes, the column showed >95% removal of chlorinated ethylenes (PCE, TCE and 1,1,-DCE) and CT. The apparent first order rate constants for all four compounds were approximately 72/hour. Chloroform was removed at a much slower rate (<32/hour) and 1,2-DCA removal was not significant. These results are also consistent with the batch studies of Lowry which showed rapid reaction of... 

The model was developed from experiments conducted in a downflow reactor, where gas residence times are greater than solid residence times. The model may not be able to predict residence time effect in a fluid bed or upflow reactor where solid residence times are greater than gas residence times. But it does give useful information for pressure and temperature effects in these reactors. 

In the once-through studies reported in the literature, a downflow reactor scheme was used for catalytic hydrocracking (9) in contrast to an upflow reactor scheme used in this study. It has been reported in the literature that an upflow reactor scheme is superior to the usual trickle-bed operation for residual feedstocks (18,19). Desulfurization, denitrogena-tion, and demetallization conversions were better in an upflow reactor. 

The well-known advantages of the slurry reactor over other types of three-phase reactors (such as trickle bed or fixed bed upflow reactor) are the following ... 

Better mixing in an upflow reactor. This may give better heat transfer, but larger axial mixing would give poorer conversion in an upflow reactor. 

High pressure drop in an upflow reactor would cause significant drop in the partial pressure of the reactant across the length of the reactor. 

High liquid holdup and liquid-to-solid ratio in an upflow reactor. High liquid holdup will offer more liquid-phase resistance to the mass transfer of the gaseous reactant to the catalyst surface. High liquid-to-solid ratio will give more importance to the role of possible homogeneous reactions. 

If reaction is rapid and highly exothermic, heat transfer between liquid and solid is more effective in an upflow reactor. 

In an upflow reactor, the catalyst must be kept in place by suitable mechanical methods, otherwise the bed will be fluidized. In a downflow reactor, the catalyst is held in place tightly by the flow. This may cause undesired cementation of the soft catalyst particles. 

In an upflow reactor, the catalyst pores are more likely to fill completely with liquid than in a downflow reactor. The catalyst effectiveness factor is lower when the catalyst pores are completely filled with liquid compared to the case when they are only partially filled with liquid. 

Better sweeping of the catalyst by liquid in an upflow reactor may sometimes give better aging of the catalyst. If a solid reactant is used (e.g., coal liquefaction) then an upflow would cause less solids plugging problems than the downflow operation. 

Cocurrent gas-liquid-solid upflow reactor (sometimes referred to as a three-phase fluidized-bed reactor) ... 

Upflow reactors are sometimes used for small scale testing. The liquid phase is the continuous phase through which the gas bubbles rise and wetting problems are absent. Industrial reactors in which liquid and gas flow upward are rarely found, because it can be difficult to keep the catalyst bed immobile at large flow rates. 

Saien R, Soleymani A R (2007), Degradation and mineralization of Direct Blue 71 in a circulating upflow reactor by UV/TiO process and employing a new method in kinetic study. J Hazard Mater, 144(l-2) 506-512... 

For the continuous fermentation in the upflow reactor, the hydrogen productivity decreased when the initial pH of the culture medium was below 6.0 (Fig. 5). Our previous batch study... 

Open Upflow Reactor (OUR) Suspended Alberici and Jaidim, 1994. 

Khadilkar, M. R., Wu, Y. X., Al-Dahhan, M. H., Dudukovic, M. P., Colakyan, M., Comparison of trickle-bed and upflow reactor performance at high pressure model predictions and experimental observations. Chemical Engineering Science, 1996, 51, 2139... 

High liquid holdup and liquid-to- olid ratio in an upflow reactor. 

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