Editor’s Choice

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Editor’s Choice

604 … NICE, 제39권 제5호, 2021

Korean Journal of Chemical Engineering, Vol.38, No.7, 1291-1307, 2021

Recent progress in metabolic engineering of Corynebacterium glutamicum for the production of C4, C5, and C6 chemicals

Baritugo KA, Son JN, Sohn YJ, Kim HT, Joo JC, Choi JI, Park SJ

Abstract - Recent environmental problems caused by petroleum-based production of chemicals have accelerated the development of biorefineries for bio-based production of chemicals. Non-pathogenic microorganism, Corynebacterium glutamicum, has extensively been engineered and used as an industrial platform host strain for the commercial production of amino acids, such as L-lysine and L-glutamate. However, only recently has it been developed beyond its use for amino acid production. Recent advances in multiomics approaches, synthetic biology tools and metabolic engineering strategies have enabled the development of recombinant C. glutamicum into a versatile microbial cell factory for biobased production of value-added platform chemicals and polymers by utilization of a broad range of biomass-derived sugars. In this review, we discuss the recent development of synthetic biology tools and techniques used for the enhancement of C. glutamicum’s ability to utilize renewable resources, specifically lignocellulosic biomass, for the production of platform chemicals with C4-C6 carbon backbone such as C4-isobutanol, 2,3-butanediol, C5-itaconic acid, 3-methyl-1-butanol, 2-methyl-1-butanol and C6-muconic acid.

Radical-driven photocatalytic transformation of organic molecules

Kim MS, Kim GM, Wang N, Lee DC

Abstract - In photocatalysis, photons are absorbed by semiconductor materials and photogenerated electrons and holes migrate to the catalytic surface for desired reactions. Photocatalytic reduction and oxidation of organic molecules pose significant challenges and opportunities, with the surging demand for energy-efficient and carbon-neutral organic synthesis. In this review, we highlight the recent progress in the expanding area of radical-driven photocatalytic transformation of organic molecules. Our focus expands from heterogeneous catalysts to quantum dots, summarizing the reaction mechanism and photocatalytic activity, in reference to conventional molecular catalysts.

A perspective on nonlinear model predictive control

Biegler LT

Abstract - Model predictive control (MPC) is widely accepted as a generic multivariable controller with constraint handling.

More recently, MPC has been extended to nonlinear model predictive control (NMPC) in order to realize high-performance control of highly nonlinear processes. In particular, NMPC allows incorporation of detailed process models (validated by off- line analysis) and also integrates with on-line optimization strategies consistent with higherlevel tasks, such as scheduling and planning. NMPC for tracking and so-called “economic”stage costs has been developed, and fundamental stability and robustness properties of NMPC have been analyzed. This perspective provides an overview of NMPC concepts and approaches, as well as the underlying optimization strategies that support the solution strategies. In addition, three challenging process case studies are presented to demonstrate the effectiveness of NMPC.

A comprehensive review of membrane fouling and cleaning methods with emphasis on ultrasound- assisted fouling control processes

Ehsani M, Doan H, Lohi A

Abstract - One of the most critical issues encountered in membrane-based separation processes is permeate flux decline in a system operating for a long period. The particles in the feed solution tend to foul the membrane surface or membrane pores, which results in pore blocking and/or cake formation on the surface. In this regard, the use of membrane cleaning techniques

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Editor’s Choice

NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 39, No. 5, 2021 … 605 for the membrane flux restoration has gained more attention. Ultrasonic (US) irradiation is an alternative technique applied to the feed solution passing across the membrane surface to either prevent the fouling formation (fouling control) or dislodge the foulants (surface cleaning). Ultrasonic cleaning mechanisms are based on sound waves travelling through the liquid, which leads to physical and chemical effects. This cleaning technique is an environmentally friendly process in which no chemical or biological agents are used. This article briefly reviews different types of fouling and classes of foulants, fouling evolution mechanisms, mathematical modelling of fouling, surface cleaning and fouling control strategies, with the emphasis on ultrasound-assisted fouling control process as an innovative cleaning method. The effect of the operational parameters on the performance of the US-assisted filtration processes, highlights, challenges, and future outlook of US cleaning will be discussed.

Nitrogen-doped graphene loaded non-noble Co catalysts for liquid-phase cyclohexane oxidation with molecular oxygenNitrogen-doped graphene loaded non-noble Co catalysts for liquid-phase

cyclohexane oxidation with molecular oxygen

Hao F, Sun Y, Wang Y, Lv Y, Liu P, Xiong W, Luo H

Selective aerobic oxidation of cyclohexane to cyclohexanone and cyclohexanol (KA oil) with high yield under mild and green conditions is still a significant challenge in the current chemical industry. Herein, nitrogen doped graphene loaded non-noble Co (Co-N-rGO) catalysts, prepared by a facile post-impregnation method, exhibited a high catalytic performance and stability in liquid phase cyclohexane oxidation with molecular oxygen. The experiment and characterization results show that N doping in the catalysts promotes Co metal particle dispersion and induces carbon film coating on Co to prevent leaching and agglomeration. Besides, density functional theory (DFT) calculations show that N doping is beneficial to the O-O bonds breaking in cyclohexyl-hydroperoxides (CHHP), thereby promoting the dissociation of CHHP and enhancing the yield to KA oil. In addition, the catalyst can be easily separated without appreciable loss of catalytic activity after recycling for five times, and show potential industrial application value for the catalytic oxidation of cyclohexane to KA oil in the chemical industry.

Techno-economic feasibility evaluation of a standalone solar-powered alkaline water electrolyzer considering the influence of battery energy storage system: A Korean case study

Niaz H, MansourLakouraj M, Liu J

Abstract - Hydrogen use is dominated by industry, with most hydrogen demand mitigated using fossil fuels; therefore, there is an eminent potential for the reduction of emissions by replacing fossil-derived hydrogen with a renewable hydrogen source.

Although the emission reduction by using renewable energy presents a promising potential, its fluctuating nature is still a challenge to be addressed. In this study, considering a battery energy storage system (BESS), a dynamic operation-based techno-economic evaluation of a standalone solar photovoltaic (PV)-powered alkaline water electrolyzer (AWE) was conducted using actual solar data. Different process configurations were designed and simulated to quantify the available potential of a standalone solar-powered hydrogen production system in Korea. Furthermore, economic evaluation metrics, such as levelized cost of hydrogen (LCOH) and Monte Carlo simulation, were used to assess the potential of different configurations under variable market prices and future technology costs to estimate the future potential. The results showed that Case 1 (standalone solar-powered AWE without BESS) offers the lowest LCOH (9.55 $/kg) but with daytime operation only. Meanwhile, Case 4 (standalone solar-powered AWE with BESS) reported the second-lowest LCOH (11.67 $/kg) compared with the other cases. The results also suggested that systems with BESS can increase operational reliability by minimizing operational fluctuations and maximizing operational hours but with a slightly higher LCOH. The conducted sensitivity analysis showed that the technology cost (solar PV, AWE, and BESS) has the highest impact on LCOH, which is promising, in light of the decreasing trend in the future costs of such technologies.