Energies

Research

13 pages, 6025 KiB

Open AccessArticle

Optimization of Nickel-Based Catalyst Composition and Reaction Conditions for the Prevention of Carbon Deposition in Toluene Reforming

by No-Kuk Park, Young Jin Lee, Byung Chan Kwon, Tae Jin Lee, Suk Hwan Kang, Bum Ui Hong and Taejin Kim

Energies 2019, 12(7), 1307; https://doi.org/10.3390/en12071307 - 05 Apr 2019

Cited by 11 | Viewed by 2701

Abstract

In this study, nickel-based reforming catalysts were synthesized for the reforming of toluene, a major component of thinners and widely used as an organic solvent. The reaction characteristics of these catalysts were investigated by both steam reforming and auto-thermal reforming. Reforming aromatic hydrocarbons [...] Read more.

In this study, nickel-based reforming catalysts were synthesized for the reforming of toluene, a major component of thinners and widely used as an organic solvent. The reaction characteristics of these catalysts were investigated by both steam reforming and auto-thermal reforming. Reforming aromatic hydrocarbons like toluene to produce synthesis gas is difficult because carbon deposition also occurs, and the deposition of carbon lowers the activity of the catalyst and causes a pressure drop during the reaction process. In order to maintain a stable reforming process, a catalytic reaction technique capable of suppressing carbon deposition is required. Steam reforming and auto-thermal reforming of toluene were used in this study, and the temperature of the catalyst bed was remarkably reduced, due to a strong endothermic reaction during the reforming process. By using scanning electric microscopy (SEM), X-ray diffraction (XRD), and temperature-programmed oxidation analysis, it is shown that carbon deposition was markedly generated due to a catalyst bed temperature decrease. In this study, optimum conditions for catalyst composition and the reforming reaction are proposed to suppress the formation of carbon on the catalyst surface, and to remove the generated carbon from the process. In addition, ceria and zirconia were added as catalytic promoters to inhibit carbon deposition on the catalyst surface, and the carbon deposition phenomena according to the catalyst’s promoter content were investigated. The results showed that the carbon deposition inhibition function of CeO₂, via its redox properties, is insignificant in steam reforming, but is notably effective in the auto-thermal reforming of toluene. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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8 pages, 1546 KiB

Open AccessArticle

Removal of HFC-134a from Brackish Water Using a Semi Batch Jet Loop Reactor

by Devi Marietta Siregar, Yiseul Park, Yong Sun Won and Jun Heok Lim

Energies 2019, 12(2), 311; https://doi.org/10.3390/en12020311 - 19 Jan 2019

Cited by 1 | Viewed by 4188

Abstract

Mineral salt components (Na⁺, Ca²⁺, K⁺, Mg²⁺, etc.) are naturally excluded during the gas hydrate in which water molecules form cavities by hydrogen bonding and guest gas molecules are encapsulated into the cavities to stabilize [...] Read more.

Mineral salt components (Na⁺, Ca²⁺, K⁺, Mg²⁺, etc.) are naturally excluded during the gas hydrate in which water molecules form cavities by hydrogen bonding and guest gas molecules are encapsulated into the cavities to stabilize the overall gas hydrate structure. However, when using refrigerant hydrofluorocarbon-134a (HFC-134a) for guest gas, it resided in resulting brackish water after the desalination process because of its high solubility in water. Jet loop reactors (JLRs) are frequently employed in many commercial applications because of their high mass transfer capabilities. In this study, a semi-batch type JLR was introduced to improve the degassing of HFC-134a from brackish water. The effect of parameters, such as the initial HFC-134a concentration (200–772 mg/L), liquid circulation (40–80 L/min) rate, and air flow rate (10–30 L/min), were studied in this JLR. The removal efficiency and overall volumetric transfer were calculated and it was determined that increasing the air flow rate has a high effect on K_La. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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10 pages, 3601 KiB

Open AccessArticle

Well-Dispersed ZnFe₂O₄ Nanoparticles onto Graphene as Superior Anode Materials for Lithium Ion Batteries

by Yiseul Park, Misol Oh and Jae Hyun Kim

Energies 2019, 12(2), 304; https://doi.org/10.3390/en12020304 - 18 Jan 2019

Cited by 7 | Viewed by 3962

Abstract

We prepared well-dispersed ZnFe₂O₄ (ZFO) nanoparticles on a graphene sheet by a facile one-step hydrothermal method using glucose as a novel linker agent and low-cost graphene flake. It was found that the glucose linkage on graphene not only prevented the [...] Read more.

We prepared well-dispersed ZnFe₂O₄ (ZFO) nanoparticles on a graphene sheet by a facile one-step hydrothermal method using glucose as a novel linker agent and low-cost graphene flake. It was found that the glucose linkage on graphene not only prevented the aggregation of ZFO particles, but also induced the exfoliation of graphene flakes. The addition of glucose during the synthesis made surface linkages on the graphene surface, and it reacted with ZFO precursors, resulting in the well-dispersed ZFO nanoparticles/graphene composite. Furthermore, the size distribution of the resultant composite particles was also shifted to the smaller particle size compared to the composite prepared without glucose. The newly prepared ZFO/graphene composite provided a higher lithium storage capability and cycle performance compared to the ZFO/graphene sample which was prepared without glucose. The good dispersion of ZFO nanoparticles on graphene and the small particle size of the composite led to markedly improved electrochemical performance. Its reversible discharge capacity was 766 mAh g⁻¹ at 1 A g⁻¹, and it also maintained as 469 mAh g⁻¹ at 6 A g⁻¹. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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10 pages, 4153 KiB

Open AccessArticle

Effect of Fines Content on Fluidity of FCC Catalysts for Stable Operation of Fluid Catalytic Cracking Unit

by Sung Won Kim, Chae Eun Yeo and Do Yeon Lee

Energies 2019, 12(2), 293; https://doi.org/10.3390/en12020293 - 18 Jan 2019

Cited by 19 | Viewed by 4332

Abstract

Effect of fines content (weight % of particles with diameter less than 45 μm) on bed fluidity was determined to get a base for good fluidization quality in the fluid catalytic cracking (FCC) unit. The fines content in equilibrium FCC catalysts (Ecat) from [...] Read more.

Effect of fines content (weight % of particles with diameter less than 45 μm) on bed fluidity was determined to get a base for good fluidization quality in the fluid catalytic cracking (FCC) unit. The fines content in equilibrium FCC catalysts (Ecat) from commercial units were controlled by adding or removing the fines to simulate commercial situation. To get the fluidity values (U_mb/U_mf) of seven different FCC catalysts (2 Ecats and 5 fresh catalysts) and their mixture, minimum fluidization velocity (U_mf) and minimum bubbling velocity (U_mb) were measured in a fluidized bed reactor (0.05 m ID). The fluidity decreased with loss of fines content and increased with increments of makeup of fresh catalysts or additive with the controlled fines content. The fluidities of catalysts increase with increases of normalized particle diameter variation by the fines addition. The obtained fluidities have been correlated with the fines contents and the catalyst and gas properties. The proposed correlation could guide to keep good catalyst fluidity in the FCC unit. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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8 pages, 2112 KiB

Open AccessArticle

Liquid-Phase Hydrogenation of Maleic Acid over Pd/Al₂O₃ Catalysts Prepared via Deposition–Precipitation Method

by Mi Yeon Byun, Ji Sun Kim, Jae Ho Baek, Dae-Won Park and Man Sig Lee

Energies 2019, 12(2), 284; https://doi.org/10.3390/en12020284 - 17 Jan 2019

Cited by 17 | Viewed by 5349

Abstract

Succinic acid (SA) is a valuable raw material obtained by hydrogenation of maleic acid (MA). The product selectivity of this reaction is highly dependent on the reaction conditions. This study therefore investigated the effect of the reaction temperature, hydrogen pressure, and reaction time [...] Read more.

Succinic acid (SA) is a valuable raw material obtained by hydrogenation of maleic acid (MA). The product selectivity of this reaction is highly dependent on the reaction conditions. This study therefore investigated the effect of the reaction temperature, hydrogen pressure, and reaction time on the liquid-phase hydrogenation of MA by a Pd/Al₂O₃ catalyst. Complete conversion of MA and 100% selectivity for SA were achieved at a temperature of 90 °C, H₂ pressure of 5 bar, and reaction time of 90 min. Fumaric acid (FA) was formed as an intermediate material by hydrogenation of MA under nonoptimal conditions. The impact of the percentage of Pd dispersion and phase of the Al₂O₃ support (γ, θ + α, and α) was also examined. The Pd/Al₂O₃ catalyst with 29.8% dispersion of Pd and γ phase of Al₂O₃ exhibited the best catalytic performance. Thus, catalytic activity depends not only on the amount of Pd dispersion but also on the physicochemical properties of Al₂O₃. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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7 pages, 1257 KiB

Open AccessArticle

Thermodynamic Analysis on the Aging of THPP, ZPP and BKNO₃ Explosive Charges in PMDs

by Kyung Min Kim, Sung Il Choi, Ki Heon Eom, Gil Hwan Ahn, Jong Gyu Paik, Byung Tae Ryu, Yong Ha Kim and Yong Sun Won

Energies 2019, 12(2), 209; https://doi.org/10.3390/en12020209 - 10 Jan 2019

Cited by 6 | Viewed by 4188

Abstract

The aging of explosive charges in pyrotechnic mechanical devices (PMDs) significantly affects the reliability of their performance. Aging decreases the explosive power of explosive charges via pre-oxidation by external sources of oxygen. In this study, the flame temperature was calculated based on the [...] Read more.

The aging of explosive charges in pyrotechnic mechanical devices (PMDs) significantly affects the reliability of their performance. Aging decreases the explosive power of explosive charges via pre-oxidation by external sources of oxygen. In this study, the flame temperature was calculated based on the amount of added oxygen source, and the effect of aging was quantified in terms of the performance of explosive charges. Three primary explosive charges (THPP, ZPP, and BKNO₃) were selected, and the explosion was assumed to have occurred in a closed adiabatic system. The flame temperature decreased with increasing oxygen addition, suggesting that the aging decreased the pressure exerted by the PMDs. The explosive power decreased in the following order: ZPP >> THPP > BKNO₃ (4100 >> 3260 > 3050 K), and it was decreased by aging as follows: ZPP >> BKNO₃ > THPP (802 >> 219 > 95 K per mole of added water). As a result, ZPP is appropriate for the generation of the huge thrust of PMDs despite its increased susceptibility to aging, while THPP is superior for reliable PMD performance. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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7 pages, 1654 KiB

Open AccessArticle

A Combined Study of TEM-EDS/XPS and Molecular Modeling on the Aging of THPP, ZPP, and BKNO₃ Explosive Charges in PMDs under Accelerated Aging Conditions

by Kyung Min Kim, Junwoo Lee, Sung Il Choi, Gil Hwan Ahn, Jong Gyu Paik, Byung Tae Ryu, Yong Ha Kim and Yong Sun Won

Energies 2019, 12(1), 151; https://doi.org/10.3390/en12010151 - 02 Jan 2019

Cited by 3 | Viewed by 3419

Abstract

The aging mechanism of explosive charges in pyrotechnic mechanical devices (PMDs) is pre-oxidations of their fuels (TiH₂ for THPP, Zr for ZPP, and B for BKNO₃) by external oxygen. The effect of water on the aging of explosive charges was [...] Read more.

The aging mechanism of explosive charges in pyrotechnic mechanical devices (PMDs) is pre-oxidations of their fuels (TiH₂ for THPP, Zr for ZPP, and B for BKNO₃) by external oxygen. The effect of water on the aging of explosive charges was thus investigated by TEM-EDS/XPS and DFT-based molecular modeling under accelerated aging with 71 °C and 100% relative humidity. The formation of oxide shell and its thickness on the surface of fuels by the aging were observed by TEM-EDS. It failed to detect any oxide on the surface of TiH₂ (no sign of Ti-O peaks in XPS) regardless of the aging time, while the thickness of oxide shell increases linearly with the time for ZPP and is saturated at a certain point for BKNO₃. It suggested that THPP is highly robust to aging compared to the others (the order of THPP >> BKNO₃ > ZPP). Then, DFT-based vacuum slab calculations visualized the diffusion of oxygen from the surface of fuels into the interior, confirming that the activation barrier for the oxygen diffusion is much lower for Zr and B than TiH₂ (37, 107, and 512 kcal/mol for Zr, B, and TiH₂, respectively), in agreement with experimental results. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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25 pages, 4125 KiB

Open AccessArticle

Considering Multiple Factors to Forecast CO₂ Emissions: A Hybrid Multivariable Grey Forecasting and Genetic Programming Approach

by Chun-Cheng Lin, Rou-Xuan He and Wan-Yu Liu

Energies 2018, 11(12), 3432; https://doi.org/10.3390/en11123432 - 07 Dec 2018

Cited by 20 | Viewed by 3142

Abstract

Development of technology and economy is often accompanied by surging usage of fossil fuels. Global warming could speed up air pollution and cause floods and droughts, not only affecting the safety of human beings, but also causing drastic economic changes. Therefore, the trend [...] Read more.

Development of technology and economy is often accompanied by surging usage of fossil fuels. Global warming could speed up air pollution and cause floods and droughts, not only affecting the safety of human beings, but also causing drastic economic changes. Therefore, the trend of carbon dioxide emissions and the factors affecting growth of emissions have drawn a lot of attention in all countries in the world. Related studies have investigated many factors that affect carbon emissions such as fuel consumption, transport emissions, and national population. However, most of previous studies on forecasting carbon emissions hardly considered more than two factors. In addition, conventional statistical methods of forecasting carbon emissions usually require some assumptions and limitations such as normal distribution and large dataset. Consequently, this study proposes a two-stage forecasting approach consisting of multivariable grey forecasting model and genetic programming. The multivariable grey forecasting model at the first stage enjoys the advantage of introducing multiple factors into the forecasting model, and can accurately make prediction with only four or more samples. However, grey forecasting may perform worse when the data is nonlinear. To overcome this problem, the second stage is to adopt genetic programming to establish the error correction model to reduce the prediction error. To evaluating performance of the proposed approach, the carbon dioxide emissions in Taiwan from 2000 to 2015 are forecasted and analyzed. Experimental comparison on various combinations of multiple factors shows that the proposed forecasting approach has higher accuracy than previous approaches. Full article

(This article belongs to the Special Issue Selected Papers from 6th Asian Conference onInnovative Energy & Environmental Chemical Engineering and The 16th Asian Conference on Fluidized‐bed and Three‐phase Reactor (ASCON‐IEEChE 2018))

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