Integrated Production of γ-butyrolactone through Coupling of Maleic Anhydride Hydrogenation and 1,4-butanediol Dehydrogenation

Design and plantwide control of an integrated plant for the hydrogenation of maleic anhydride and the dehydrogenation of 1,4-butanediol has been studied for the synthesis of γ-butyrolactone in an adiabatic reactor, under different conditions of reaction temperatures and hydrogen to feed ratio, realizing optimal hydrogen utilization and better energy efficiency. Compared to stand-alone processes, the integrated process has several advantages, e.g., easy temperature control, improved γ-butyrolactone yield, good energy efficiency and optimal hydrogen utilization. The stability and robustness of the process is checked by rigorous dynamic simulation in AspenDynamics

Advanced Characterization of Silica–Encapsulated Aluminum Pigments

For environmental reasons, the paints industry shifts from solvent-borne towards water-borne formulations. This change is challenging the business of aluminum pigments, as the hydrogen released by the reaction of aluminum with water degrades the optical properties, besides being a safety concern. In this work, industrial-grade aluminum pigments are encapsulated, by a well-known method, in a silica matrix by sol-gel process using isopropanol - a more suitable solvent for the industry. The effectiveness of the encapsulation process is proven by advanced physical methods (Scanning Electron Microscopy, Energy Dispersive X-Ray Analysis, Selected Area Electron Diffraction, Fourier Transformed InfraRed Spectroscopy, Thermo-Gravimetric Analysis) and by industry-relevant tests (stability in water, hiding power, flop and granulometry). Moreover, advanced surface-applied physical methods (High Resolution Transmission Electron Microscopy combined with Selected Area Electron Diffraction and Scanning Transmission Electron Microscopy, and FT-IR microscopy) clearly show the homogeneity of the resulting pigments, a quality which is highly desirable for practical applications. The results demonstrate that stability comparable to that of pigments passivized by chromium-based inhibitors is easily achieved, for a variety of operating conditions. However, accomplishing a homogeneous silica layer of the right thickness is the determining factor for good optical properties

Design and Control of Di n-Pentyl Ether Process

Recycle of un-converted reactants is a common practice in industrial chemical processes. However, the material recycle induces a non-linear behaviour of the plant which often manifests as high sensitivity of the recycle flow rates with respect to disturbances such as changes in raw material quality, production rate and uncertain design parameters. This non-linear behaviour of the system is often the source of control difficulties. Thus the importance of appropriate control structure in reactor-separation-recycle is evident. The case study of di n-pentyl ether production illustrates two control strategies that can be applied to processes involving one reactant and one recycle. The strategy based on self-regulating reactant inventory uses the plant-inlet flow rate as the dominant variables which significantly affects the production rate. The strategy based on inventory feedback control uses the reactor inlet flow rate, the reactor holdup or the reaction temperature / pressure as throughput manipulator. For the di n-pentyl ether process, both strategies are applicable, as demonstrated by rigorous dynamic simulation

Integrated design and control of plantwide systems coupling exothermic and endothermic reactions

The problem of integrated design and control of plantwide systems coupling endothermic and exothermic reactions is addressed. Processes simultaneously carrying on the endothermic first-order reaction A -> R + Qand the exothermic second-order reaction B + Q -> P are considered. As the physical properties of the species involved vary, possible flowsheets are identified and feasible control strategies are suggested. Multiple steady states are detected at fixed values of the plantwide-control variables. Singularity theory is exploited to divide the space of reactor-design parameters into regions characterized by qualitatively different solution diagrams. The implications of the observed behaviour on plant controllability are thoroughly discussed. (C) 2009 Elsevier Ltd. All rights reserved

Eco-efficient downstream processing of biobutanol by enhanced process intensification and integration

The biobutanol stream obtained after the fermentation step in the acetone-butanol-ethanol process has a low concentration (less than 3 wt % butanol) that leads to high energy usage for conventional downstream separation. To overcome the high downstream processing costs, this study proposes a novel intensified separation process based on a heat pump (vapor recompression)-assisted azeotropic dividing-wall column (A-DWC). Pinch analysis and rigorous process simulations have been used for the process synthesis, design, and optimization of this novel sustainable process. Remarkably, the energy requirement for butanol separation using heat integration and vapor recompression assisted A-DWC is reduced by 58% from 6.3 to 2.7 MJ/kg butanol