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Dynamic controls of an extractive distillation (ED) process and a partially heat-integrated pressure-swing distillation (PHIPSD) process for separating a mixture of 50 mol % ethanol and 50 mol % tetrahydrofuran are investigated. Comparisons between the control structures of the two distillation processes are made. The results show that PHIPSD has advantages of economic savings and control compared with the ED process. In addition, some control structures of PHIPSD for feed streams with different composition and some comparisons between the performances of the control structures are also studied. It is concluded that the feed composition mainly impacts the dynamic control structures of PHIPSD through the different combinations of auxiliary heat exchanger and that a composition controller can improve the control performances.

The mixture of n-heptane and isobutanol creates a minimum-boiling azeotrope under atmospheric conditions. Extractive distillation was used for separating n-heptane and isobutanol. A sequential iterative optimization procedure optimized the steady state extractive distillation process to obtain a minimal total annual cost (TAC). The dynamic control of the optimal extractive distillation process showed poor controllability. It was found that the dynamic control performance could be improved if the solvent flow rate was increased properly with a small increase in TAC. Hence, the choice of the optimal extractive distillation process for separating a binary azeotropic mixture should be considered from the perspectives of both TAC and the dynamic control performance.

Coal is an important energy source in the world, and its chemical structure is the basis of its application, especially for its pyrolysis and liquefaction. Supercritical ethanolysis is a type of chemical extraction that can effectively depolymerize some weak bonds in organic matter. In this work, new insights into the primary products of Naomaohu coal were studied with supercritical ethanolysis. The non-covalent and weak covalent bonds (such as ether and ester bonds) in the coal were broken to yield small molecular compounds (SMCs) with a conversion of 70.3% (dry and ash-free basis) at 370 °C. SMCs, including esters, alcohols, aldehydes, ethers, ketones, hydrocarbons (aromatic and aliphatic hydrocarbons), acids, phenols, and heteroatom compounds, were identified quantitively through gas chromatography/mass spectrometry. Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance were used to characterize the structure of the coal and its ethanolysis residues. The structure characteristic of the coal was deduced through analyzing the SMCs and residues. Interestingly, the SMCs can reflect the primary reaction products of the coal during its pyrolysis or liquefaction.

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