Catalytic conversion of large molecules: Effect of pore size and concentration

Abstract

packings tested, it is probably unfair to make a precise comparison packings in the proper column diameter: packing diameter ratio to be as good or better than perforated or bubble cap plates.When 1,5-pentanediol is the extractive distillation agent, the perforated plate column gives a separation of an apparent relative volatility of ethyl acetate to ethanol of 3.19. With helices it is 2.32; with addles, 2.08; with Intalox addles, 2.02; a d with Raschig rings, 2.08. These data show that, although packed columns may not be quite as efficient as perforated plate columns, they can indeed be used in extractive distillation. LITERATURE CITED with &Orated dates' Further research probably show certain Berg, L,, "spration of Ethylbenzene from and m-~ylene by ti^^ and K ; , K ; are defined numerically in Glandt (1981) as functions of h. C, is defined as C,,, = 1 / N~d~. For our subsequent analysis, we have fitted a sixth-order polynomials to the curves of Kf and K ; vs. h and have found K ; ---aX + bh2 + cX3 + dX4 + eX5 + fX6, Ko

Effect of reactant size reductions on catalytic reaction rates

“…Thus, the effects of pore size on diffusivity and on surface area are in opposition, and as a result there exists an optimal pore size (or optimal value of ) at which the observed reaction rate is maximized. This has been verified experimentally (Shimura et al, 1986; Spry and Sawyer, 1975) and theoretically (Rajagopalan and Luss, 1979; Ruckenstein and Tsai, 1981; Do, 1984).…”

“…Note that the advantages of a staged catalytic reactor for the relatively simple systems considered here might not be realized in a practical system (e.g., heavy oil hydroprocessing) where coke and metals deposit on the catalyst and the reactant molecules have a distribution of sizes, change by different proportions, and possess different reactivities. An additional complicating factor is that, if the equilibrium partition coefficient is a function of concentration, then reactant depletion in a fixed bed reactor can also influence the optimal value of and hence the manner in which the catalyst pore size should vary down the reactor (Do, 1984). Nevertheless, the analysis presented here can serve as a foundation for more detailed models that address these issues.…”

“…The literature provides several physical and mathematical models that have incorporated the effects of configurational diffusion on catalytic reaction rates. These models have probed the influence of the catalyst pore size and pore size distribution (Shimura et al, 1986;Rajagopalan and Luss, 1979; Spry and Sawyer, 1975;Do, 1984;Young and Rajagopalan, 1985), catalyst pellet size and geometry (Chang and Crynes, 1986;Rajagopalan and Luss, 1979), changes in pore geometry (Prasher et al, 1978b; Rajagopalan and Luss, 1979; Guin et al, 1986; Chang and Crynes, 1986), reactant concentration (Do, 1984), and reactant size distributions (Spry and Sawyer, 1975) on the apparent reaction rate. However, a feature omitted in previous models is the effect of reactant size reductions on the apparent reaction rate.…”

Mathematical analysis of physicochemical phenomena in the catalyst during hydrogenating depolymerization of coal extract benzene insoluble fraction

“…The problem of optimizing the pore radius in the case of large molecule conversion on the intrinsic surface of the grain was examined by Rajagopalan and Luss (1979), and also by Ruckenstein and Tsai (1981), DO (1984) [32 -34]. The existence of an optimal pore radius can be inferred from the fact that the increase in its value has two conflicting effects: the intrinsic surface of the grain decreases, and the rate of reactant diffusion to the active sites on that surface increases.…”

The effect of rotational masking on optimum pore size

“…Their results for petroleum residua indicate an optimum pore size on the order of twice the molecular diameter. A further analysis of optimal pore size was recently presented by Do (1984). In this study, the effect of the bulk concentration on the optimum pore size was examined by relating the pore surface concentration to the bulk concentration by a nonlinear partition expression developed by Glandt (1981).…”