Catalytic multitubular reactor

Ethylene and synthesis gas are used to produce propionaldehyde and formaldehyde. These aldehydes then are reacted in the presence of a catalyst to form methacrolein. The methacrolein reacts with atmospheric oxygen to form meth-acrylic acid in a catalytic multitubular reactor. The methacrylic acid is separated from water (a byproduct) and purified it then reacts with methanol to form MMA. The byproducts are incinerated on-site to recover the energy in the process [41]. 

Separability. One of the greatest advantages of a solid catalyst is that it can be separated easily from the products of reaction. To do this successfully requires careful control of the process conditions so that exposure of the catalyst to nonreactant liquids capable of affecting or dissolving either the catalytic material or the support is prevented or rninimi2ed. Solid catalysts typically are used in axial or radial flow beds and multitubular reactors. Many successful commercial processes maintain the reactants and products in the gas phase while in contact with the catalyst to avoid catalyst degradation problems. 

Metal monoliths show good thermal characteristics. A typical support with herringbone channels made from Fecralloy performed satisfactory in automotive applications [27]. Modeling showed that overall heat transfer was about 2 times higher than for conventional pellets [28,29]. Hence, there is potential for structured catalysts for gas-phase catalytic processes in multitubular reactors. 

Fig. 7a. (a) A packed bed reactor, (b) A multitubular packed bed reactor, (c) A catalytic gauze reactor. 

In addition to the harmonization of the underlying physical and chemical processes, the catalytic-plate heat exchanger offers a cost-effective alternative to both conventional multitubular reactors and catalytic microreactors for industrial... 

Hence, there is potential for structured catalysts for catalytic conversions of gas-phase reactants in multitubular reactors. Scientists from... 

FIGURE CS4.1 Computed concentration and temperature profiles in the multitubular reactor for the catalytic reduction of nitrobenzene to aniline. 

In this example the design or simulation of a multitubular reactor for catalytic hydrocarbon oxidation is discussed (Froment [76]). The case considered here is of a rather complex nature, that is. 

Process Description. Reactors used in the vapor-phase synthesis of thiophene and aLkylthiophenes are all multitubular, fixed-bed catalytic reactors operating at atmospheric pressure, or up to 10 kPa and with hot-air circulation on the shell, or salt bath heating, maintaining reaction temperatures in the range of 400—500°C. The feedstocks, in the appropriate molar ratio, are vaporized and passed through the catalyst bed. Condensation gives the cmde product mixture noncondensable vapors are vented to the incinerator. 

Cybulski, A., Eigenberger, G., and Stankiewicz, A., Operational and structural nonidealities in modeling and design of multitubular catalytic reactors, Ind. Eng. Chem. Res. 36, 3140-3148 (1997). 

Single-phase catalytic fixed bed reactors are the main reactor type used for large-scale heterogeneously catalyzed gas-phase reactions. Frequently, multitubular... 

Figure 1. Basic types of catalytic fixed-bed reactors. A) Adiabatic fixed-bed reactor B) Multitubular fixed-bed reactor.

MSG Cnstina, C M G S Batista, J G V F Sousa, J A A M Castro, Modelling Multitubular Catalytic Reactors the Influence of Shell Side Flow , Chem Eng Set... 

Description The flowsheet for an oxygen-based unit is one of several possible process schemes. Compressed oxygen, ethylene and recycle gas are mixed and fed to a multitubular catalytic reactor (1). The temperature of oxidation is controlled by boiling water in the shell side of the reactor. 

The drawback of randomly packed microreactors is the high pressure drop. In multitubular micro fixed beds, each channel must be packed identically or supplementary flow resistances must be introduced to avoid flow maldistribution between the channels, which leads to a broad residence time distribution in the reactor system. Initial developments led to structured catalytic micro-beds based on fibrous materials [8-10]. This concept is based on a structured catalytic bed arranged with parallel filaments giving identical flow characteristics to multichannel microreactors. The channels formed by filaments have an equivalent hydraulic diameter in the range of a few microns ensuring laminar flow and short diffusion times in the radial direction [10]. 

It is the model library for fixed-bed catalytic reaction, fluidised-bed and various polymer reactors and so on. Different tools are available in gPROMS software for simulation and modelling of various systems. Some of the following are (i) multi-scale modelling of complex processes and phenomena, (ii) State-of-the-art model validation tools allow estimation of multiple model parameters from steady-state and dynamic experimental data, and provide rigorous model-based data analysis, (iii) The maximum amount of parameter information from the minimum number of experiments, (iv) The gPROMS-CFD Hybrid Multitubular interface provides ultimate accuracy in the modelling of... 

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