MODELING OF TRICKLE BED REACTOR

Abstract

The last decade a clear trend has been set in chemical industry towards safe, clean and energy efficient production methods. Routes to accomplish this include at chemical side the development of new, highly selective catalysts, and at the engineering side the integrated approach to improved or new processes. Process intensification is currently the fashionable phrase and includes multifunctional and fixed bed reactors. These approaches meet where catalysts are applied in a fixed way in a reactor. Trickle bed reactor is an example of the fixed bed reactor. The trickle bed reactors are widely used in petroleum, petrochemical, chemical industries (hydrogenation, oxidation etc.), electrochemical, biochemical processes etc. which makes it on the most popular catalytic reactor among the all. Reactor modeling demonstrates the advantages of this reactor concept, which include the low-pressure drop, plug flow liquid behaviour high active surface area and easy catalyst handling and catalyst regeneration. In the present study, the modeling of trickle bed reactor for the two reactions namely hydrogenation and oxidation has been carried out. The hydrogenation and oxidation reactions, both are one of the important reactions in the chemical industries. Two systems have been chosen for the modeling namely the hydrogenation of xylose to xylitol with Ru/C catalyst and oxidation of aqueous phenol solution with Ex-1144.8 catalyst (comprising the oxides of copper, zinc and cobalt). In this thesis, a one-dimens al, steady state mathematical models has been developed for the simulation of isothermal trickle bed reactor. The effect of different parameters like temperature, pressure superficial velocity, and surface rate constants has been discussed. These models comprises the set of ordinary differential equations and also a set of non linear algebraic equations. To solve them numerically constitutive properties, kinetic rate equation and other input data pertaining to the system are taken from the literature. The set of ordinary differential equations are solved by Runge-Kutta Method, and similarly non-linear algebraic equations are solved by Newton-Raphson Method. By simulation of reactor, it is concluded that the xylose concentration in the reactor decreases as pressure increases but increases as liquid velocity increases. In case of oxidation of phenol, the effects of liquid velocity, reaction temperature and surface rate constant on phenol conversion have been studied. The estimated results conclude that phenol hi conversion increases with temperature and surface rate constant but decreases as liquid velocity increases. The obtained results from the simulation on the hydrogenation of xylose to xylitol with Ru/C catalyst and oxidation of aqueous phenol solution with Ex-1144.8 catalyst has been validated with the data available in the literature.