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- 저자 : John N. Kuhn (검색결과 3 건)
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CO2 separation from biogas using PEI-modified crosslinked polymethacrylate resin sorbent
Olusola Johnson,Babu Joseph,John N. Kuhn 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-
The separation of CO2 from biogas to achieve vehicle/pipeline grade methane is an expensive step. Recently, PEI (polyethyleneimine) impregnated resins have been proposed and evaluated for CO2 separationfrom flue gases and air. However, its use in biogas upgrading and evaluation of the economic feasibilityof such adsorbents have not been explored in detail. In this work, by modifying an inert polymericresin (HP2MGL) using PEI, CO2 was separated from biogas. The sorbent exhibited the highest adsorptioncapacity of 2.7 mmolCO2/gads at 30% PEI loading, increasing to 2.9 mmolCO2/gads in the presence of moisture,and remained stable for up to five adsorption–desorption cycles. In situ DRIFTS studies showed thatCO2 adsorption on PEI-impregnated sorbent is consistent with the zwitterion reaction mechanism, andthe sorbent could be regenerated completely at 100 C. The upgrading cost of biogas is primarily dominatedby the operating cost of regeneration and the adsorbent cost. The economic feasibility analysis suggeststhat PEI-impregnated resin sorbent requires less capital and operating costs than conventionalbiogas upgrading technologies. Therefore, PEI-impregnated polymeric resins are promising for CO2 separationfrom biogas.
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Understanding the Effects of Surface Finish on Diffusion Bonding of AZ31 Alloys
Matthew Criado,Abhijit Roy,John Ohodnicki,Nicholas Tondravi,Hannah Fischer,Alejandro Almarza,Howard A. Kuhn,Prashant N. Kumta 대한용접접합학회 2023 대한용접·접합학회지 Vol.41 No.5
Methods to optimize the diffusion bonding (DB) process while also creating lap joints were investigated using AZ31, the commercial Mg alloy, focusing primarily on studying the effects of varying conventional process parameters and more importantly, exploring the influence of surface roughness on creating an acceptable strong bond. The results indicate that when contact is made between surface areas of roughness (Ra > 0.2 ㎛) diffusion is facilitated at reduced process parameters of time and temperature. Furthermore, this early bond initiation combined with the optimized DB process parameters results in a stronger bond with strengths increasing by ~ 150% in comparison to the DB samples created with a smooth surface finish. Additionally, less than 20% total overall distortion is observed while preserving a uniform microstructure of consistent grain sizes in the material over the entire joining region compared with the parent material.
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Hanzhong Shi,Venkat R. Bhethanabotla,John N. Kuhn 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.118 No.-
Perovskite oxides, such as La0.5Ba0.5FeO3 (LBF), are promising materials for converting CO2 to CO throughlow-temperature reverse water–gas shift chemical looping (RWGS-CL). To transition toward industrialization,this study focused on forming perovskite-oxide/silica composite pellets (25 wt% LBF) with sufficientlyhigh crushing strength, with materials prepared by extrusion and tableting methods. X-rayfluorescence (XRF) and diffraction (XRD) confirmed that the resulting material is 26.6 wt% LBF on SiO2with a combined structure of LBF and SiO2 components. Temperature-programmed reduction (TPR)and oxidation (TPO) experiments revealed that CO2 is converted to CO at 550 C by LBF/SiO2 pellets,higher than LBF by 50 C. CO2 chemisorption was determined to be 62.2 lmol/gLBF. DRIFTS-MS experimentsconfirmed that adsorbed CO2 is dissociated to CO. High material stability is proven by longtermRWGL-CL experiments combined with XRD and XPS. The CO2 to CO yields were 2.21, 2.41, and2.35 mmol/gLBF of 10 mm tableting pellets, 6 mm tableting pellets, and extrusion pellets, respectively. Deactivated pellets are able to be regenerated by air thermal treatment following intentional reduction. All pellets showed stable redox properties in 50 cycles of semi-batch reactor experiments, indicating thatLBF/SiO2 pellets are candidate materials for further scale-up evaluation.
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