Gas-Liquid-Solid Phase

One of the most interesting and green continuous flow techniques to be developed emerged from the ability to perform triphasic reactions, whereby a gas-liquid phase is pumped through a packed ed containing a heterogeneous catalyst. Using this 

---

Due to the complexity of mass transfer between gas-liquid-solid phases, it is difficult to evaluate the average value of mass transfer coefficient ki from the literature. A realistic way to evaluate ki is to use the algebraic expression of solution and by regression to obtain the experimental data rather than by regression with solving the set of non-linear differential equations. 

Multiphase Reactors Reactions between gas-liquid, liquid-liquid, and gas-liquid-solid phases are often tested in CSTRs. Other laboratory types are suggested by the commercial units depicted in appropriate sketches in Sec. 19 and in Fig. 7-17 [Charpentier, Mass Transfer Rates in Gas-Liquid Absorbers and Reactors, in Drew et al. (eds.), Advances in Chemical Engineering, vol. 11, Academic Press, 1981]. Liquids can be reacted with gases of low solubilities in stirred vessels, with the liquid charged first and the gas fed continuously at the rate of reaction or dissolution. Some of these reactors are designed to have known interfacial areas. Most equipment for gas absorption without reaction is adaptable to absorption with reaction. The many types of equipment for liquid-liquid extraction also are adaptable to reactions of immiscible liquid phases. 

Heterogeneous reactions occur in gas or liquid phase or in both phases in the presence of a solid as a catalyst or as reactant, which depends on the process in use. Usually, the reactions in gas-solid phase or gas-liquid-solid phases depend on the industrial reaction conditions. In catalytic processes, the catalyst promotes the reaction rate in... 

Hunkapiller MW, Hood LE, and Dreyer WJ (1981) A gas liquid solid phase peptide and protein sequenator. Journal of Biological Chemistry 256 7990-7997. 

For proper design and simulation of HDT reactors, kinetic and reactor modeling are aspects that need to be deeply studied however, this is not a trivial task due to the numerous physical and chemical processes that occur simultaneously in the reactor phase equilibrium, mass transfer of reactants and products between the gas-liquid-solid phases, diffusion inside the catalyst particle, a complex reaction network, and catalyst deactivation. Ideally, the contribution of all these events must be coupled into a robust reactor performance model. The level of sophistication of the model is generally defined based upon the pursued objectives and prediction capability [4]. 

The formulation of the model equations is based on the transport of reactants between the gas-liquid-solid phases that takes place in TBRs [51]. Hydrogen, being the main gaseous reactant, is first transferred from the gas phase to the liquid bulk. The reactants in the liquid phase (chemical lumps and dissolved H2) travel to the catalyst particle in order to react Products such as H2S and CH4 are released to the gas phase passing through the liquid phase, whereas hydrocarbon products return to the liquid. 

Yamanaka I, Eunakawa A, Otsuka K (2004) Electro-catalytic synthesis of DMC over the Pd/VGCF membrane anode by gas-liquid-solid phase-boundary electrolysis. J Catal 221 110-118... 

---