Communications - Effect of Catalyst Particle Size on Performance of a Trickle Bed-Reactor

Colorimetric evaluation of the efficiency of liquid-solid contacting in trickle flow

“…Satterfield and Ozel (1975), based on data from Bondi (1971), defined the wetting efficiency as the ratio between the reaction rate constants obtained in trickle-bed and stirred tank reactors. A similar definition was proposed by Koros (1976), Montagna et al (1977), and Van Klinken and Van Dongen (1980), among others. Schwartz et al (1976) is the first author who measured the wetting efficiency by using a two-tracer method (one adsorbable and the other nonadsorbable).…”

A Comparison of Current Models for Isothermal Trickle-Bed Reactors

“…These observations include: i) dry areas on a portion of the catalyst surface with either stagnant liquid or actively flowing liquid present on the remaining surface (7-10), ii) no dry area is present on the catalyst surface, instead, the catalyst surface is covered by a combination of stagnant liquid films and actively flowing liquid (7,(11)(12)(13), and iii) the entire catalyst surface and internal catalyst pores may be completely dry as a result of liquid reactant evaporation at reactor conditions (9,14-15) Some of the remaining studies did not necessarily observe incomplete catalyst wetting, but included this concept either directly as an adjustable parameter in the model to fit the observed conversion versus liquid mass velocity data, (7,9,13,(16)(17)(18), or indirectly via use of a correlation for liquid-solid contacting established for non-porous absorber column packings (11,(19)(20). Table I depend upon the magnitude of the intrinsic reaction rate.…”

“…Table I depend upon the magnitude of the intrinsic reaction rate. Petroleum hydrodesulfurization (19)(20)(21), certain types of petroleum hydrogénations (22),' or chemical decomposition reactions (11) are liquid-limiting and proceed slowly enough that only internal particle diffusion or combined pore diffusion and liquid-to-solid resistances are controlling. Chemical Hydrogénation of α-methylstyrene to cumene on Pd catalyst Hydrogénation of cyclohexene to cyclohexane using 3% Pd and 5% Pt-on-carbon catalysts Deuterium exchange between hydrogen and water using 0.2% Pd-on-carbon Hydrogénation of 1,5 cyclo-octadiene in cyclooctane using 38% Ni-on-kieselguhr Hydrogénation of α-methylstyrene to cumene using 0.5% and 2.5% Pd-on-alumina Hydrogénation of 2-butanone using Ru-on alumina Hydrogénation of nitrobenzene on 1% Pd Hydrogénation of cyclohexene to cyclohexene on 5% Pd-on-carbon Hydrogénation of diolefins Hydrogénation of α-methylstyrene to cumene on 0.5% Pd-on-alumina Oxidation of sulfur dioxide on activated carbon Hydrogénation of α-methylstyrene to cumene using Pd-on-alumina hydrogénations at low to moderate pressures (8-10»14-18, 23-26) or oxidations (7_,_13,_27 28) are usually gaseous reactant limiting and involve more active catalysts so that both internal and external transport processes or the latter ones only are controlling.…”

Effect of Catalyst Particle Size on Performance of a Trickle-Bed Reactor

“…Dev. 1980, 19, 328 Ql = volumetric liquid flowrate, cm3/s -rA = rate of conversion of A, mol of A/(s) (cm3 of liquid holdup) V = volume of reactor bed, cm3 xA = conversion fraction of A ow = wetted area of catalyst particles per unit volume of bed, cm2/cm3 ot = total area of catalyst particle per unit volume of bed, cm2/cm3 « = catalyst bed void fraction = catalyst effectiveness factor µ , = viscosity of liquid, g/(cm)(s) vL = kinematic viscosity of liquid, cm2/s Pl = density of liquid, g/cm3 ir = 3.1415-Sir: In our opinion Marangozis (1980) has not only confused the purpose of our paper (Montagna et al, 1977) but has also misunderstood the aim of our other papers on the same subject (Paraskos et al, 1975; Montagna and Shah, 1975). Our reasons are as follows.…”

“…(1) The purpose of the paper by Montagna et al (1977) was to discriminate between holdup and effective wetting models in pilot plant reactors. These two correlating models predict different dependence of conversion (or more specifically In (CAi/CAq), where CAi and CAo are the reactor inlet and outlet concentrations) on the catalyst particle diameter.…”