For methanol synthesis

Future Methanol Processes. The process route for methanol synthesis has remained basically unchanged since its inception by BASF in 1923. The principal developments have been in catalyst formulation to increase productivity and selectivity, and in process plant integration to improve output and energy efficiency while decreasing capital cost. 

Autothermal reactor for methanol synthesis using a numerical search technique... 

Examples for calculated heat transfer coefficients are shown in the table on Figure 1.5.1 The physical and other properties are used from the UCKRON-1 Example for methanol synthesis. These properties are ... 

For a first test of the reactor and all associated service installations it is recommended that experiments for methanol synthesis should be carried out even if this reaction is not especially interesting for the first real project. The reason for this recommendation is that detailed experimental results were published on methanol synthesis (Berty et al, 1982) made on a readily available catalyst. This gives a good basis of comparison for testing a new system. Other reactions that have been studied in detail and for which the performance of a catalyst is well known can also be used for test reactions. 

The catalyst should be the copper-based United Catalyst T-2370 in 3/16 , reduced and stabilized, in extrudate form. Initially, 26.5 g of this should be charged to the catalyst basket. This catalyst is not for methanol synthesis but for the low temperature shift reaction of converting CO to CO2 with steam. At the given conditions it will make methanol at commercial production rates. Somewhat smaller quantity of catalyst can also be used with proportionally cut feed rates to save feed gas. 

Only parts needed above but for the vapor-phase reactor are listed here. Most of the description for the installation for methanol synthesis experiments (Figure 4.2.1) holds for this installation, too. In the mentioned unit, product was blown down while still hot, thus keeping all product in a single vapor phase. This simplifies material balance calculations. When avoiding condensation is difficult, cooling and separation becomes necessary. This method was used in the cited AIChEJ publication. 

A.2 Explicit Form of the Rate Equation for Methanol Synthesis by the UCKROH-1 Test Problem... 

The UCKRON AND VEKRON kinetics are not models for methanol synthesis. These test problems represent assumed four and six elementary step mechanisms, which are thermodynamically consistent and for which the rate expression could be expressed by rigorous analytical solution and without the assumption of rate limiting steps. The exact solution was more important for the test problems in engineering, than it was to match the presently preferred theory on mechanism. 

Fig ure 6-12. Profiles of equilibrium oonversion Xg versus temperature T for methanol synthesis. (Source Schmidt, L. D., The Engineering of Chemioal Reaotions, Oxford University Press, New York, 1998.)... 

Figure 5-4. A block flow diagram showing the combined reforming for methanol synthesis. ...

The hydrogenation of dioxomethylene, step (33) is, most likely, the rate-limiting step, although the hydrogenation of formate in (32) is a also candidate. By assuming that Eqs. (24), (23) and (29) are slow for the water-gas shift reaction and that (33) is slow for methanol synthesis, we arrive at the following set of equations, in which one site is assumed to consist of two copper atoms ... 

Figure 8.14. Turnover frequency for methanol synthesis from H2 and CO2 at 18 bar and 523 K as a function ofZn coverage on polycrystalline copper. [From j. Nakamura, I. Nakamura,...

In the Discussion period, it was emphasised that C02 played an important role in the ICI process for methanol synthesis. Tom Wilkie, the Science Correspondent of The Independent newspaper, was present and the following day, 22 August 1990, the following headline appeared in the newspaper ... 

A further important industrial reaction is the water-gas shift reaction [Eq. (75)] which provides a way of increasing H2 CO ratios, or of producing pure H2. Pure H2 is needed for ammonia synthesis, 2H2 ICO is needed for methanol synthesis, and 3H2 lCO is used for synthesis of substitute natural gas. 

Figure 8.3 Proposed reaction mechanism for methanol synthesis on Pd and comparison with gas-phase mechanism surface intermediates are speculative and associated energies are estimates...

Standard state, for molecules, 24 687—688 Standard state enthalpy change for methanol synthesis, 25 305 Standard-state heat, 24 688 Standard-state heat of reaction, 24 688 Standards-writing organizations, 15 760 Standard Test Conditions (STC), 23 38 Standard test methods, 15 747—748 Standpipe pressure profiles, 11 818 Standpipes, in circulating fluidized beds, 11 817-819 Stand-retting, 11 606 Stannane, 13 613, 24 813... 

L. Ma, D.L. Trimm and M.S. Wainwright Promoted skeletal copper catalysts for methanol synthesis, in Advances of Alcohols Fuels in the World, - Proceedings of the XII International Symposium on Alcohol Fuels, Beijing, China, Tsinghua University Press, 1998, pp. 1-7. 

Figiu 3-18 Plot of equilibrium conversion Xq versus temperatiwe for methanol synthesis starting witii stoichiomeh ic feed. While die equilibriimi is favorable at ambient temperature, die conversion rapidly decreases at higher temperature, and industrial reactors operate with a Cu/ZnO catalyst at pressures as high as 100 atm. 

Depending on the nature of the raw material (coal, natural gas, naphtha), both the reaction conditions of gasification, and the employment of reforming (shift conversion) will determine the composition of the syngas. For instance, synthesis gas produced from coal normally has a H2 C0 ratio of unity and therefore the ratio has to be adjusted to 2.0 prior to the use of the gas for methanol synthesis. Accordingly, syngas derived from CH4 bears a cost advantage for the needed ratio of 2.0. 

The mechanism for methanol synthesis from mixtures of H2, CO and CO2 over supported Cu catalysts have been studied extensively in the literature using a number of chemical methods (Bell et al 1995). One of the key issues has been the role of CO and CO2 in maintaining the carbon supply for methanol synthesis or interconversion betwen the two via the water-gas shift reaction ... 

Unpromoted Cu/Si02 is found to have a low activity for methanol synthesis from H2/CO mixtures, whereas an increased activity from H2/CO2. Alkali metal promotion increases the activity for methanol synthesis from the H2/CO mixtures, probably due to the increase in surface OH groups engaged in the formation of the formate species which are the precursors to the methanol. Cu/Si02 powder catalysts (with 5 wt% Cu) can be prepared by ion exchange of silica with Cu(NOs)2 in aqueous solution, followed by calcination and reduction. Such preparations contain very fine Cu particles ( 0.5 nm) on a powdered silica support as revealed by HRTEM. 

Because of the pure performance of traditional Cu catalysts in the hydrogenation of C02, efforts have been made to find new, more effective catalysts for direct C02 hydrogenation. The problem is to improve selectivity, specifically, to find catalysts that display high selectivity toward methanol formation and, at the same time, show low selectivity in the reverse water-gas shift reaction, that is, in the formation of CO. It appears that copper is the metal of choice for methanol synthesis from C02 provided suitable promoters may be added. Special synthesis methods have also been described for the preparation of traditional three-component Cu catalysts (Cu-ZnO-A1203 and Cu-Zn0-Cr203) to improve catalytic performance for C02 reduction. 

The same integration strategy has also been used [64] to find the optimal Cu Zn Al ratio in mixed oxide catalysts for methanol synthesis from Syngas. 

Omata et al. have investigated catalysts for methanol synthesis from C02-rich synthetic gas under pressurized conditions [22]. They tested 96 mixed-oxide catalysts composed of Cu, Zn, Al, Cr, Zr, Ga at random ratio. Each catalyst was placed in a... 

Fig. 8.16 (a) Parallel reactor with 96 tubes for methanol synthesis from... 

Catalysts from Slid Chemie were applied for methanol steam reforming by Stimming et al. [121], G66-MR, a general-purpose catalyst containing 11% Al, 37% Cu and 52% Zn with 121 m2 g 1 surface area, and C18-HA, a catalyst optimized for methanol synthesis containing 2-3% Al, 50-60% Cu and 25-35% Zn with... 

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