Different operational modes, various scales and complex phenomena make the design of a chemical process a challenging task. Besides conducting basic lab experiments and deriving fundamental kinetic and thermodynamic models, a crucial task within the entire process design is the synthesis of an optimal reactornetwork constituting the core of a chemical process. However, instead of directly up-scaling the process to large devices, it is wise to investigate process characteristics on miniplant-scale. For an existing miniplant for the hydroformylation of 1-dodecene using a rhodium catalyst and a thermomorphic solvent system for catalyst recovery, two optimized reactor designs are derived. Suitable reactor-networks were synthesized by applying the Flux Profile Analysis approach introduced in Kaiser et al. (2017). The combination of a first reactor with dynamic/distributed control options and a subsequent backmixed CSTR arose to be the most promising configurations. The technical design under miniplant conditions were carried out for two possible realizations of this network, namely (i) a continuous flow reactor and (ii) a periodically operated semibatch reactor, both followed by the existing CSTR which was originally operated in the miniplant. An optimization of the two optimal reactor configurations within an overall process including a Page 1 of 53 ACS Paragon Plus Environment Industrial & Engineering Chemistry Research liquid-liquid phase separation for catalyst recovery and a distillation column for separating the solvents and reactant evinced a selectivity w.r.t. the linear aldehyde around 94 % and a conversion around 98 %. This is a large improvement of the process performance of 24 % linear aldehyde selectivity and 40 % conversion when using the existing CSTR.
Volumetric mass transfer coefficients and Bodenstein numbers (Bo) for the elongated bubble flow regime in horizontal helically-coiled tube reactors are reported using two different measurement techniques (oxygen optodes, and optical observation of an oxygen-sensitive dye). Additionally, the gas-liquid mass transfer and the residence time behavior of the two-phase flow were described with a 3D Computational Fluid Dynamics (CFD) model, and also with a onedimensional two-phase model. For this study, 16 cases involving different gas and liquid volumetric flow rates were employed to generate air-water flows through two helically coiled tubes with curvature ratios of δ 1 = 0.093 and δ 2 = 0.3, respectively. The superficial gas and liquid Reynolds numbers (Re s,G and Re s,L) and the gas holdup (ϵ G) are varied from 494 to 2483, from 1456 to 2713, and from 0.46 to 0.81, respectively. The mass transfer measurements show an increasing gas-liquid mass transfer rate with increasing superficial velocity of the liquid-phase and Re s,G. The Bodenstein number decreases with increasing gas-phase Reynolds number and increases with increasing superficial velocity of the liquid-phase. Correlations describing the mass transfer and backmixing behavior are proposed. The CFD results are in excellent agreement with the experimental data. With the 1D two-phase model it is possible to describe the residence time behavior of the two-phase flow through the helically coiled tube.
Innovative
reactor concepts show evidence to significantly improve
the reaction performance in comparison to conventional reactor systems.
To evaluate the reactor concepts, experimental investigation of the
process behavior is indispensable. In this contribution, a reactor
tandem comprising a repeatedly operated semibatch reactor (RSBR) followed
by a continuously stirred tank reactor (CSTR) is analyzed for the
hydroformylation of 1-dodecene. This reactor tandem was suggested
by N. M. Kaiser et al. [Ind. Eng. Chem. Res. 2017, 56, 11507–11518] to increase
the selectivity toward the linear aldehyde at high conversion levels
of 1-dodecene. An additional degree of freedom is gained because of
the combined utilization of a batchwise and continuously operated
reactor. By using a dynamic process model for planning of the experiments,
comparability is ensured with studies of a single CSTR from literature.
The experiments confirm an increase in conversion and target product
yield applying the RSBR + CSTR tandem, so that up to 90% selectivity
is achieved with closed byproduct recycle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.