Catalytic simulated distillation

Figure 4. Simulated distillation of sample No. 1693 and bulk products from catalytic cracking of low severity (2123) and high severity (2124).

The present economic and environmental incentives for the development of a viable one-step process for MIBK production provide an excellent opportunity for the application of catalytic distillation (CD) technology. Here, the use of CD technology for the synthesis of MIBK from acetone is described and recent progress on this process development is reported. Specifically, the results of a study on the liquid phase kinetics of the liquid phase hydrogenation of mesityl oxide (MO) in acetone are presented. Our preliminary spectroscopic results suggest that MO exists as a diadsorbed species with both the carbonyl and olefin groups coordinated to the catalyst. An empirical kinetic model was developed which will be incorporated into our three-phase non-equilibrium rate-based model for the simulation of yield and selectivity for the one step synthesis of MIBK via CD. 

The catalytic performances obtained during transalkylation of toluene and 1,2,4-trimethylbenzene at 50 50 wt/wt composition over a single catalyst Pt/Z12 and a dualbed catalyst Pt/Z 121 HB are shown in Table 1. As expected, the presence of Pt tends to catalyze hydrogenation of coke precursors and aromatic species to yield undesirable naphthenes (N6 and N7) side products, such as cyclohexane (CH), methylcyclopentane (MCP), methylcyclohexane (MCH), and dimethylcyclopentane (DMCP), which deteriorates the benzene product purity. The product purity of benzene separated in typical benzene distillation towers, commonly termed as simulated benzene purity , can be estimated from the compositions of reactor effluent, such that [3] ... 

Kreul LU, Gorak A, Dittrich C, Barton PI. Dynamic catalytic distillation advanced simulation and experimental validation. Computers Chem Eng 1998 22 371-378. 

Yuxiang Z, Xien X. Study on catalytic distillation processes. Part B. Simulation of catalytic distillation processes—quasi-homogenous and rate-based model. Trans IChemE 1992 70 465 470. 

Figure 6.15 presents a compact flowsheet based on catalytic distillation, as simulated with Aspen Plus [9], Benzene and propylene are fed in countercurrent in... 

Several of the commercial simulation programs offer preconfigured complex column rigorous models for petroleum fractionation. These models include charge heaters, several side strippers, and one or two pump-around loops. These fractionation column models can be used to model refinery distillation operations such as crude oil distillation, vacuum distillation of atmospheric residue oil, fluidized catalytic cracking (FCC) process main columns, and hydrocracker or coker main columns. Aspen Plus also has a shortcut fractionation model, SCFrac, which can be used to configure fractionation columns in the same way that shortcut distillation models are used to initialize multicomponent rigorous distillation models. 

Wang, E. Li, C. Simulation of suspension catalytic distillation for the synthesis of linear alkyl benzene. Chin. J. Chem. Eng. 2003,11 (5), 520-525. 

Huang, C. Yang, L. Ng, F.T.T. Rempel, G.L. Application of catalytic distillation for the aldol condensation of acetone a rate-based model in simulating the catalytic distillation performance under steady-state operations. Chem. Eng. Sci. 1998, 53 (19), 3489-3499. 

Y Zheng, FTT Ng, GL Rempel. Catalytic distillation A three-phase nonequilibrium model for the simulation of the aldol condensation of acetone. Ind Eng Chem Res. 40 5342-5349, 2001. 

Specialised units are used to simulate complex fractionation processes in petroleum refining. Typical configuration consists of a main column with pump-around and side strippers (Fig. 3.14). Among applications, we may cite pre-flash tower, crude atmospheric distillation, or Fluid Catalytic Cracking (FCC) main fractionator. 

Figure 70.13 Experimental and simulated liquid distillate compositions (all 11 test runs) for the column with the reactive section filled with catalytic structured packing Montz Multipak.

Figure 10.17 represents a comparison of the concentration profiles in two different ethyl acetate synthesis modes, with and without a decanter. The investigation is performed for the pilot-scale column, with a molar feed ratio acetic acid/ethanol equal to 1.2, reflux ratio equal to 3, and a total feed rate equal to 30kg/h. The distillate-to-feed ratio is set to 0.9. The simulations reveal that the conversion with the liquid-liquid separator is about 5% higher that without a decanter, since there is less water and more acetic acid in the catalytic section. Improved conversion and product enrichment due to liquid-liquid separation result in a significant (29%) improvement of the product purity. Finally, because there is less condensed water in the reflux to be evaporated, the heat duty is reduced by up to 26%. 

Simulation of Catalytic Distillation Processes-Quasi-Homogeneous and Rate-Based Model, Trans. IChemE, 1992, 70,465-470. 

L. U. Kreul, A. Gorak, C. Dittrich, P. I. Barton, Dynamic Catalytic Distillation Advanced Simulation and Experimental Validation, Comp. Chem. Eng., 1998, 22, S371-S378. 

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