Design Catalytic hydrogenation

The experiments were run to determine how four experimental variables influence the yield of tetrahydrofuran in catalytic hydrogenation of furan over a palladium catalyst. The variables and the experimental domain are shown in Table 5.10. 

The experimental design and the yields, y, obtained are given in Table 5.11. 

If the objective is to determine the experimental condition for maximum yield, this 

However, this was not the only objective. It was also desired to determine the influence of the variables, as well as their interactions. Thus, a second order interaction model was assumed to give a satisfactory description, i.e. 

This means that three- and four-factor interaction effects were assumed to be small compared to the experimental error. The model contains 11 parameters and the experimental design contains 16 runs. The excluded higher order interaction effects allow an estimate of the residual sum of squares, SSE, which will give an estimate of the experimental error variance, s with 16 - 11 = 5 degrees of freedom. This estimate can then be used to compute confidence limits for the estimated model parameters so that their significance can be evaluated. 

---

The lack of the use of catalyst library design tools in the field of heterogeneous catalytic hydrogenation inspired us to describe our approach used in this area. In this presentation we shall depict our complex approach to design, optimize and mapping catalyst libraries. 

Figure 5.28. In situ wet-ETEM of real-time catalytic hydrogenation of nitrile liquids over novel Co-Ru/Ti02 nanocatalysts, (a) Fresh catalyst with Co-Ru clusters (arrowed at C). The support is marked, e.g., at u. (b) Catalyst immersed in adiponitrile liquid and H2 gas in flowing conditions growth of hexamethylene diamine (HMD) layers (at the catalyst surface S in profile, arrowed) at 81 °C, confirmed by composition analysis and mass spectrometry, (c) ED pattern of HMD in (b) in liquid environments. Further growth is observed at 100 °C. The studies show that wet-ETEM can be used to design a catalytic process (after Gai 2002). (d) Scaled up reactivity data for novel Co-Ru/Ti02 nanocatalysts confirming wet-ETEM studies of high hydrogenation activity of the nanocatalyst (2). Plots 1 and 3 are the data for Raney-Ni complexes and Ru/alumina catalysts, respectively.

Concerning activity, most studies focus on intrinsic (chemical) kinetics, with little consideration to the apparatus and its possible physical limitations. In fact,the design and selection of a catalytic hydrogenation reactor (hydrogenator) is not a trivial problem at all, owing to the broad range of process conditions encountered. 

H-Oil process a catalytic process that is designed for hydrogenation of heavy feedstocks in an ebullated bed reactor. 

In another example, a new catalyst has been discovered which is ideal for use in the catalytic hydrogenation of nitrohydrocarbons by a continuous process. It has an enormous potential for increasing the business of the company. Unfortunately, the current plant was designed to handle batch processes and is unsuitable for modification. The generation of capital to construct the plant is a problem for the company. 

In the above equations the symbols A, B, C, D designate phenol, hydrogen, cyclohexanone and cyclohexanol. Table 5.7 presents the model parameters at 423 K and 1 atm. The model takes into account the effect of the products on the reaction rate in the region of higher conversion. This feature is particularly useful for describing the product distribution in consecutive catalytic-type reactions. Note that the adsorption coefficients are different in the two reactions. Following the authors, this assumption, physically unlikely, was considered only to increase the accuracy of modeling. 

The Michael addition of malonates to cyclic enones, catalyzed by chiral Ru( 6-arcnc)(p-lolucncsulfonyl-1,2-diaminc), has been performed to afford the adduct with excellent enantiomeric excess [91,92]. A related catalyst was designed to perform sequentially the Michael addition to cyclic enone and the enantioselective hydrogenation of the ketone. Thus, the chiral ruthenium catalyst B containing trans hydride and borohydride ligands was able to enan-tioselectively (96% ee) promote the Michael addition of malonate to cyclo-hexenone. Further in situ catalytic hydrogenation (400 psi H2) was performed and led to excellent diastereoselectivity trans/cis 30/1 [93] (Scheme 43). 

---