自产气气提与纤维床反应器耦合发酵生产丁醇

采用发酵产物中的二氧化碳（CO₂）和氢气（H₂）作为循环气提气源,对丙酮丁醇梭菌（Clostridium acetobutylicum CGMCC 5234）发酵产物进行原位气提,实现丙酮、丁醇和乙醇混合物（ABE）的连续纤维床固定化发酵生产。连续发酵实验进行了12批次共309 h,总溶剂ABE当量浓度为133.3 g·L^-1（其中丁醇 83.5 g·L^-1,丙酮38.4 g·L^-1,乙醇11.4 g·L^-1）,葡萄糖消耗率为1.29 g·（L·h） ^-1,总溶剂ABE产率为0.431 g·（L·h） ^-1,转化率为0.333 g·g^-1,其中丁醇产率为0.270 g·（L·h） ^-1,转化率为 0.209 g·g^-1,发酵液中丁醇浓度控制在8～12 g·L^-1,显著优于游离发酵的结果。气提提取之后冷凝的ABE溶液出现分层现象,其中丁醇相丁醇浓度高达603.7 g·L^-1,极大地减缓后续分离提纯的负担。结果表明,自产气循环气提与纤维床固定化耦合连续发酵生产ABE（特别是丁醇）的工艺具有可行性和竞争力。     

Assessment of in situ butanol recovery by vacuum during acetone butanol ethanol (ABE) fermentation

BACKGROUND: Butanol fermentation is product limiting owing to butanol toxicity to microbial cells. Butanol (boiling point: 118 °C) boils at a higher temperature than water (boiling point: 100 °C) and application of vacuum technology to integrated acetone–butanol–ethanol (ABE) fermentation and recovery may have been ignored because of direct comparison of boiling points of water and butanol. This research investigated simultaneous ABE fermentation using Clostridium beijerinckii 8052 and in situ butanol recovery by vacuum. To facilitate ABE mass transfer and recovery at fermentation temperature, batch fermentation was conducted in triplicate at 35 °C in a 14 L bioreactor connected in series with a condensation system and vacuum pump. RESULTS: Concentration of ABE in the recovered stream was greater than that in the fermentation broth (from 15.7 g L^?1 up to 33 g L^?1). Integration of the vacuum with the bioreactor resulted in enhanced ABE productivity by 100% and complete utilization of glucose as opposed to a significant amount of residual glucose in the control batch fermentation. CONCLUSION: This research demonstrated that vacuum fermentation technology can be used for in situ butanol recovery during ABE fermentation and that C. beijerinckii 8052 can tolerate vacuum conditions, with no negative effect on cell growth and ABE production. Copyright © 2011 Society of Chemical Industry     

Synthesis and optimization of membrane cascade for gas separation via mixed‐integer nonlinear programming

Currently, membrane gas separation systems enjoy widespread acceptance in industry as multistage systems are needed to achieve high recovery and high product purity simultaneously, many such configurations are possible. These designs rely on the process engineer's experience and therefore suboptimal configurations are often the result. This article proposes a systematic methodology for obtaining the optimal multistage membrane flow sheet and corresponding operating conditions. The new approach is applied to cross‐flow membrane modules that separate CO₂ from CH₄, for which the optimization of the proposed superstructure has been achieved via a mixed‐integer nonlinear programming model, with the gas processing cost as objective function. The novelty of this work resides in the large number of possible interconnections between each membrane module, the energy recovery from the high pressure outlet stream and allowing for nonisothermal conditions. The results presented in this work comprise the optimal flow sheet and operating conditions of two case studies. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1989–2006, 2017     

Comparison of stochastic methods with respect to performance and reliability of low‐temperature gas separation processes

In this paper, the performances of two popular stochastic methods, the genetic algorithm (GA) and simulated annealing (SA), are verified in the optimization of low‐temperature gas separation processes. While the feasibility of GA optimization of low‐temperature processes has recently been addressed, our work studied the quality of GA solutions. Having optimized the solutions of three different case studies, it was observed that SA is more robust and reliable than GA when applied to such systems, and by adjusting the key parameters in the SA method, the optimization process can avoid pre‐mature convergence and is able to give the best near‐global results.     

Application of high‐pressure swing adsorption process for improvement of CO2 recovery system from flue gas

Although the super cold separator applied to the system for CO₂ recovery from flue gas can produce pure CO₂ liquid, the CO₂ recovery efficiency is low. Therefore, the addition of a PSA plant was considered for the secondary CO₂ recovery from the noncon‐densing gas to improve the efficiency. The PSA plant was operated for adsorption at the same pressure as that of the super cold separator and for desorption at the atmospheric pressure. From both the simulation and the experimental data, it was confirmed that CO₂ could be concentrated from 50% in the noncondensing gas to 70% in the recovery gas by the PSA plant and the CO₂ recovery efficiency of the plant was about 90%.     

Compatibility of PTET‐60/CA blends and separation performance of their membranes for benzene/cyclohexane mixture by pervaporation

Aromatic copolyester of poly(trimethylene‐co‐ethylene terephthalate) (PTET) with different composition was synthesized and the PTET sample with 60% weight fraction of polytrimethylene (PTET‐60) was amorphous. The compatibility of PTET‐60/cellose acetate (CA) blends and the pervaporation of their membranes for separation of benzene/cyclohexane mixtures were investigated. It was found that PTET‐60 is compatible with CA when the weight fraction of PTET‐60 in PTET‐60/CA blends (W_PTET‐60) is lower than 0.35 and more than 0.5. Both the degree of swelling (DS) and the permeation flux (J) of these blend membranes increased with increasing W_PTET‐60 from 0 to 0.35, and a maximum value of the separation factor (α) displayed at W_PTET‐60 = 0.25. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2832–2838, 2006     

Toward more cost‐effective and greener chemicals production from shale gas by integrating with bioethanol dehydration: Novel process design and simulation‐based optimization

A novel process design for a more cost‐effective, greener process for making chemicals from shale gas and bioethanol is presented. The oxidative coupling of methane and cocracking technologies are considered for converting methane and light natural gas liquids, into value‐added chemicals. Overall, the process includes four process areas: gas treatment, gas to chemicals, methane‐to‐ethylene, and bioethanol‐to‐ethylene. A simulation‐optimization method based on the NSGA‐II algorithm for the life cycle optimization of the process modeled in the Aspen HYSYS is developed. An energy integration model is also fluidly nested using the mixed‐integer linear programming. The results show that for a “good choice” optimal design, the minimum ethylene selling price is $655.1/ton and the unit global‐warming potential of ethylene is 0.030 kg CO₂‐eq/kg in the low carbon shale gas scenario, and $877.2/ton and 0.360 kg CO₂‐eq/kg in the high carbon shale gas scenario. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1209–1232, 2015     

Rapid and large‐scale separation of magnetic nanoparticles by low‐field permanent magnet with gas assistance

Bubbles can be used to greatly improve the speed of magnetic separation (MS) and overcome the limitation of magnetic force on the capture distance, making low‐field MS highly efficient and easily scalable. This novel method leads to the development of a medium‐free continuous gas‐assisted magnetic separator on small pilot scale using low‐field permanent magnet. This separator is demonstrated highly efficient for recovery of proteins‐loaded magnetic nanoparticles from large volume biosuspension. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3101–3106, 2014     

Effect of dodeca‐tungstophosphric acid on morphology and performance of polyvinyl alcohol membrane for gas separation

In this article, organic/inorganic membrane was prepared for gas separation by incorporating dodeca‐tungstophosphric acid (PWA) into the base polymer. Flat‐sheet composite membranes were produced via dry‐phase inversion method. In the first stage, the effects of PWA concentration on morphology and performance of polyvinyl alcohol (PVA) membranes were elucidated. For this stage, the preparation of membranes was carried out at constant temperature of 40°C. The porosity of the prepared membrane was slightly increased with addition of PWA. By increasing the PWA concentration up to 6 wt % in the membrane recipe, the permeability of N₂, O and air was improved from 50,000 (for no addition of PWA) to around 160,000, 140,000, and 80,000 L m^?2 h^?1, respectively. For H this was enhanced from 110,000 to 230,000 L m^?2 h^?1. The ideal selectivity of the membrane was slightly improved for N₂/air (from 1 to 1.2). For N₂/O₂ pair, the initial drop (from 2.5 to 1.5) was followed by a slight increase (1.5–1.9). Moreover, the selectivity was decreased for H₂/air (from 2.8 to 1.8) and H₂/N₂ (from 2.2 to 1.7) by increasing the PWA concentration. The 10 wt % PVA membrane with 6 wt % PWA demonstrated superior performance compared with the other compositions. In summary, the presence of PWA in the casting solution results in lower flux for O₂ and higher selectivity for H₂/O₂ pair. In the second stage, the effects of solvent evaporation temperature (10, 27, 40, and 80°C) on morphology and performance of the membranes were studied. By increasing the temperature, the number and size of voids were increased. The permeation of gases was improved from 100,000 L m^?2 h^?1 (at 10°C) to 150,000 (O₂), 250,000 (air), 380,000 (N₂), and 600,000 L m^?2 h^?1 (H₂) by increasing the temperature up to 80°C. This increment resulted in selectivity alteration either increment or diminishment. The selectivity was changed from 1.3 to 3.2 (H₂/O₂), 0.8–2.5 (N₂/O₂), 1.2–2.4 (H₂/air), 0.6–1.5 (N₂/air) and 2.0–1.5 (H₂/N₂). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Comparison between supported gas membrane process and supported liquid membrane process for the separation of NH3 from aqueous media containing NH3 and CO2

A comparison between the hollow fibre supported gas membrane (SGM) process and the hollow fibre supported liquid membrane (SLM) process for the separation of NH₃ from aqueous solutions containing NH₃ and CO₂ was performed. The experimental data as well as the model simulation demonstrate that the SLM process can remove NH₃ from aqueous solutions of NH₃ and CO₂ at a higher rate than the SGM process when the NH₃ loading is low or the ratio of NH₃ to CO₂ is low. This study suggests that the proper combination of the SGM process and the SLM process can strip NH₃ more effectively from aqueous solutions containing NH₃ and CO₂.     

Morphology,dynamic mechanical properties,and gas separation of crosslinking silica‐containing polyimide nanocomposite thin film

Silica‐containing polyimide (PI‐Si) crosslinked hybrid films are synthesized and applied to gas separation application. The PI‐Si hybrid films are prepared from 4,4′‐diaminodiphenyl ether (ODA), 3, 3′‐oxydiphthalic anhydride (ODPA), p‐aminophenyltrimethoxysilane (APTS), and phenyltrimetoxysilane (PTS). The monomer of monoamide APTS is used to modulate the block chain length of ODA–ODPA and then form bonding between PTS and ODA–ODPA phases. In the series of xASPI (where x indicates the molecular weight (in kg/mol) of PI block chain length of ODA–ODPA and ASPI denotes PI modified with APTS) hybrid films, the glass transition temperature (T_g) increases and α‐relaxation damping peak intensity decreases with the increase of APTS content. Meanwhile, the gas permeabilities of O₂ and N₂ of xASPI films are slightly higher as compared with pure PI. The other series of (5AS–y‐S)PI (5ASPI incorporates with PTS and y is the weight of PTS) hybrid films, the properties of T_g, density, and α‐relaxation damping peak intensity are decreased with increasing the PTS content. However, higher O₂ and N₂ gas permeabilities and O₂/N₂ selectivity are achieved by increasing the PTS content in (5AS–y‐S)PI hybrid films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007