One step fabrication of carbon supported cobalt pentlandite (Co9S8) via the thermolysis of lignin and Co3O4

Kwon, Gihoon,Cho, Dong-Wan,Tsang, Daniel C.W.,Kwon, Eilhann E.,Song, Hocheol Elsevier Science B.V. Amsterdam 2018 Journal of CO<SUB>2</SUB> utilization Vol.2018 No.27

Pyrolysis of aquatic carbohydrates using CO₂ as reactive gas medium: A case study of chitin

Kwon, Gihoon,Tsang, Daniel C.W.,Oh, Jeong-Ik,Kwon, Eilhann E.,Song, Hocheol Elsevier 2019 ENERGY Vol.177 No.-

<P><B>Abstract</B></P> <P>Here in this study, the thermolysis of aquatic biopolymer (<I>i.e.,</I> chitin) was mainly investigated as a strategic means for reinforcing the insecure supply chains of terrestrial biomass. To maximize carbon utilization in the carbon substrate and establish a sustainable pyrolysis platform, this study particularly employed CO<SUB>2</SUB> as reactive gas medium. To this end, this study laid great emphasis on elucidating the mechanistic role of CO<SUB>2</SUB> in pyrolysis of chitin. For the fundamental study, the thermolysis of chitin in CO<SUB>2</SUB> in reference to the case in N<SUB>2</SUB> was characterized thermo-gravimetrically. A series of the TGA tests signified that the homogeneous reactions between solid-state chitin and CO<SUB>2</SUB> should be excluded. However, a lab-scale pyrolysis of chitin in CO<SUB>2</SUB> demonstrated that CO<SUB>2</SUB> enhanced thermal cracking of the volatile hydrocarbon species from the thermolysis of chitin. In parallel, CO<SUB>2</SUB> reacted with the volatile hydrocarbon species to form CO. To justify such genuine mechanistic roles of CO<SUB>2</SUB>, two-stage pyrolysis of chitin was conducted, and all experimental findings strongly supported the genuine mechanistic roles of CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pyrolysis of chitin was conducted to recovery energy. </LI> <LI> To establish a sustainable pyrolytic platform, CO<SUB>2</SUB> was used as reactive gas medium. </LI> <LI> CO<SUB>2</SUB> offered a strategic means for maximize the carbon utilization. </LI> <LI> CO<SUB>2</SUB> provided a favorable condition for enhancing thermal cracking. </LI> <LI> CO<SUB>2</SUB> reacted with volatile hydrocarbons to form CO. </LI> </UL> </P>

Catalytic pyrolysis of low-rank coal using Fe-carbon composite as a catalyst

Kwon, Gihoon,Park, Young-Kwon,Ok, Yong Sik,Kwon, Eilhann E.,Song, Hocheol Pergamon 2019 Energy Conversion and Management Vol. No.

<P><B>Abstract</B></P> <P>In this study, CO<SUB>2</SUB>-cofeeding pyrolysis of low-rank coal (LRC) was performed to quest the mechanistic effects of CO<SUB>2</SUB> on the CO enhancement. The thermogravimetric analysis (TGA) test and lab-scale pyrolysis of LRC informed that CO<SUB>2</SUB> and tar were reacted by the gas phase reaction. The gas phase reaction of CO<SUB>2</SUB> and tar led to the different carbon distribution in liquid pyrolysate, and it was experimentally justified by mass balance of three pyrogenic products and the CO enhancement. To expedite the CO enhancement by CO<SUB>2</SUB>, the catalytic capability of LRC char was also investigated. For the fundamental study, inorganics in LRC was removed through the acid-washing process, which experimentally proved that the catalytic capability was imparted from inorganics in LRC. All findings in this study suggested that the exploitation of CO<SUB>2</SUB> in pyrolysis of LRC offers the better opportunity in terms of the CO<SUB>2</SUB> conversion into CO. Also, the CO enhancement can be further expedited catalytically. Such facts greatly offer a technical benefit that the exploitation of LRC in reference to high rank coal (HRC) can be an ideal carbon source because the CO<SUB>2</SUB> susceptibility resulting in the CO<SUB>2</SUB> enhancement by consuming tar is highly dependent on the volatile carbon content.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO<SUB>2</SUB> to fuel was achieved by pyrolysis of low rank coal. </LI> <LI> CO<SUB>2</SUB> mitigated tar generation. </LI> <LI> CO enhancement by gas phase reaction between and CO<SUB>2</SUB> and tar. </LI> <LI> Catalytic enhancement of CO by inorganics in low rank coal. </LI> <LI> Low rank coal can be an ideal feedstock for CO<SUB>2</SUB>-cofeeding pyrolysis. </LI> </UL> </P>

Effects of calcium carbonate on pyrolysis of sewage sludge

Kwon, Eilhann E.,Lee, Taewoo,Ok, Yong Sik,Tsang, Daniel C.W.,Park, Chanhyuk,Lee, Jechan Elsevier 2018 ENERGY Vol.153 No.-

<P><B>Abstract</B></P> <P>This study demonstrates that calcium carbonate (CaCO<SUB>3</SUB>) allows not only enhancement of the production of CO as syngas, but also reduction of the content of polycyclic aromatic hydrocarbons (PAHs) in the pyrolytic products from sewage sludge. CO<SUB>2</SUB> was formed by the decomposition of CaCO<SUB>3</SUB> in pyrolysis. The CO<SUB>2</SUB> derived from CaCO<SUB>3</SUB> enhanced thermal cracking of volatile organic carbons (VOCs) generated during the pyrolysis of sewage sludge and provided an additional source of C and O, likely enhancing the production of CO at >650 °C. In addition, more solid product was converted into gaseous and liquid products by the addition of CaCO<SUB>3</SUB> in the pyrolysis of sewage sludge. This work suggests that CaCO<SUB>3</SUB> can be used as an inexpensive source of CO<SUB>2</SUB> that increases thermal efficiency of the pyrolysis process and reduces the evolution of harmful chemical species such as PAHs during thermal treatment of the byproduct during processing at municipal and industrial wastewater treatment facilities (<I>i.e.</I>, sewage sludge).</P> <P><B>Highlights</B></P> <P> <UL> <LI> CaCO<SUB>3</SUB> is used as an additive to pyrolysis feedstock to enhance energy recovery. </LI> <LI> Addition of CaCO<SUB>3</SUB> to sewage sludge decreases the content of PAHs in pyrolytic product. </LI> <LI> CaCO<SUB>3</SUB> helps yield more gaseous and liquid pyrolytic products in pyrolysis of sewage sludge. </LI> </UL> </P>

CO₂ to Fuel via Pyrolysis of Banana Peel

Dohee Kwon,Sangyoon Lee,Eilhann. E. Kwon 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

이산화탄소 활용 촉매 열분해를 통한 폐섬유의 고부가 가치화

권도희 ( Dohee Kwon ),정성엽 ( Sungyup Jung ),이상윤 ( Sangyoon Lee ),권일한 ( Eilhann E. Kwon ) 한국폐기물자원순환학회(구 한국폐기물학회) 2021 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2021 No.-

합성 섬유의 발명 이후 우리의 삶의 질은 향상되었다. 그러나 합성 섬유는 생분해성이 없고 업사이클 및 재활용이 어려우므로 누적 생산량과 처리량은 중요하다. 섬유를 세탁하는 과정에서 신흥 오염물로 간주하는 미세 플라스틱이 환경으로 방출된다. 미세 플라스틱의 공급원 감소를 위한 수단으로 이 연구는 폐섬유를 부가가치 제품으로 전환하는 신속한 처리 플랫폼을 제안한다. 이를 위해 폐섬유의 촉매 열분해를 수행했으며 더욱 환경 친화적인 공정을 위해 폐섬유 열분해의 원료로 이산화탄소를 사용했다. 이산화탄소 환경에서 폐섬유의 열분해 결과, 합성 가스와 메탄이 생성되었으며 이산화탄소는 폐섬유의 열분해로 인해 발생한 휘발성 화합물과의 기상 반응을 통해 추가적인 일산화탄소를 생성했다. 반응 속도를 촉진하여 더 많은 양의 합성 가스를 생성하기 위해 코발트 기반 촉매를 이용하여 촉매 열분해를 수행했다. 이산화탄소를 이용한 비촉매 열분해보다 촉매 열분해는 수소와 일산화탄소의 생산량이 각각 3배와 8배 더 높았다. 또한, 이 공정은 촉매 비활성화를 억제했으며 80 wt. % 이상의 폐섬유를 합성가스와 메탄으로 전환했다. 이산화탄소를 원료로써 사용하여 일산화탄소를 더 많이 생성할수록 벤젠 유도체 및 다환방향족 탄화수소와 같은 유해 화학종의 형성을 최소화하는 효과적인 수단을 제공한다.

일회용 플라스틱 식품 용기의 이산화탄소 활용 열처리 연구

권도희(Dohee Kwon),정성엽(Sungyup Jung),박경남(Gyeongnam Park),권일한(Eilhann E. Kwon) 대한환경공학회 2022 대한환경공학회 학술발표논문집 Vol.2022 No.11

Fabrication of spherical biochar by a two-step thermal process from waste potato peel

Yang, Xiao,Kwon, Eilhann E.,Dou, Xiaomin,Zhang, Ming,Kim, Ki-Hyun,Tsang, Daniel C.W.,Ok, Yong Sik Elsevier 2018 Science of the Total Environment Vol.626 No.-

<P><B>Abstract</B></P> <P>The aim of this study was to develop a new approach for the preparation of spherical biochar (SBC) by employing a two-step thermal technology to potato peel waste (PPW). Potato starch (PS), as a carbon-rich material with microscale spherical shape, was separated from PPW as a precursor to synthesizing SBC. The synthesis process comprised (1) pre-oxidization (preheating under air) of PS at 220 °C and (2) subsequent pyrolysis of the pretreated sample at 700 °C. Results showed that the produced SBC successfully retained the original PS morphology and that pre-oxidization was the key for its shape maintenance, as it reduced surface tension and enhanced structural stability. The SBC possessed excellent chemical inertness (high aromaticity) and uniform particle size (10–30 μm). Zero-cost waste material with a facile and easy-to-control process allows the method to be readily scalable for industrialization, while offering a new perspective on the full use of PPW.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Potato starch (PS) derived from potato peel waste (PPW) has highly regular spherical shape. </LI> <LI> PS morphology was retained with pre-oxidation process after pyrolysis. </LI> <LI> PS's spherical shape affords great homogeneity to the produced biochar. </LI> <LI> Mechanism of shape maintenance was studied via various spectral characterizations. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effective Role of Carbon Dioxide in the Pyrolysis of Organic Waste: CO₂-to-Fuels and Chemical Species Control

Taewoo Lee,Eilhann E. Kwon 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

Polycyclic aromatic hydrocarbons and volatile organic compounds in biochar and biochar-amended soil: a review

Dutta, Tanushree,Kwon, Eilhann,Bhattacharya, Satya Sundar,Jeon, Byong Hun,Deep, Akash,Uchimiya, Minori,Kim, Ki-Hyun Wiley (Blackwell Publishing) 2017 Global change biology. Bioenergy Vol.9 No.6

<P>Residual pollutants including polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and carbon (aceous) nanoparticles are inevitably generated during the pyrolysis of waste biomass and remain on the solid coproduct called biochar. Such pollutants could have adverse effects on the plant growth as well as microbial community in soil. Although biochar has been proposed as a 'carbon negative strategy' to mitigate the greenhouse gas emissions, the impacts of its application with respect to long-term persistence and bioavailability of hazardous components are not clear. Moreover, the co-occurrence of low molecular weight VOCs with PAHs in biochar may exert further phytotoxic effects. This review describes the basic need to unravel key mechanisms driving the storage vs. emission of these organics and the dynamics between the sorbent (biochar) and soil microbes. Moreover, there is an urgent need for standardized methods for quantitative analysis of PAHs and VOCs in biochar under environmentally relevant conditions. This review is also extended to cover current research gaps including the influence of biochar application on the short- and long-term fate of PAHs and VOCs and the proper control tactics for biochar quality and associated risk.</P>