PTMSP[Poly(1-trimethylsilyl-1-propyne)]에 LDH (layered double hydroxide)의 함량을 0, 1, 3, 5 wt%로 달리하여 PTMSP/LDH 복합막을 제조하고, PTMSP/LDH 복합막의 LDH 함량에 따른 H2, N2, CH4, C3H8, n-C4H10의 기체투과도와 선 택도를 조사하였다. PTMSP/LDH 복합막의 LDH 함량이 0∼5 wt%로 증가하면 H2와 N2의 투과도는 점차 감소하였고, n-C4H10의 투과도는 급격히 증가하였다. 그리고 CH4와 C3H8의 투과도는 0∼3 wt% 범위에서는 감소하고 3∼5 wt% 범위에서 는 증가하였다. PTMSP/LDH 복합막의 LDH 함량이 5 wt%로 증가하면 H2와 N2에 대한 H2, N2, CH4, C3H8, n-C4H10의 선택 도는 점차 증가하였고, CH4에 대한 C3H8과 n-C4H10의 선택도는 0∼3 wt% 범위에서는 증가하고, 3∼5 wt% 범위에서는 감 소하였다. PTMSP/LDH 복합막의 CH4과 n-C4H10의 투과도가 증가하면 H2와 N2에 대한 CH4과 n-C4H10의 선택도는 증가하였 고, n-C4H10의 투과도가 증가하면 CH4에 대한 n-C4H10의 선택도는 n-C4H10의 투과도 182,000 barrer까지는 증가하다가 그 이상 에서는 감소하였다. C3H8의 투과도가 증가하면 H2와 N2에 대한 C3H8의 선택도는 C3H8의 투과도 46,000∼50,000 barrer 범위에 서는 감소하고 50,000∼52,300 barrer 범위에서 증가하였고 52,300∼60,000 barrer 범위에서는 감소하였다. 그리고 C3H8의 투과 도가 증가하면 CH4에 대한 C3H8의 선택도는 52,300 barrer까지는 급격히 감소하였고, 그 이상에서는 급격히 증가하였다.

The effects of a Ni coating on the sensing properties of nano ZnO:Ni based gas sensors were studied for CH4 and CH3CH2CH3 gases. Nano ZnO sensing materials were prepared by the hydrothermal reaction method. The Ni coatings on the nano ZnO surface were deposited by the hydrolysis of zinc chloride with NH4OH. The weight % of Ni coating on the ZnO surface ranged from 0 to 10 %. The nano ZnO:Ni gas sensors were fabricated by a screen printing method on alumina substrates. The structural and morphological properties of the nano ZnO : Ni sensing materials were investigated by XRD, EDS, and SEM. The XRD patterns showed that nano ZnO : Ni powders with a wurtzite structure were grown with (1 0 0), (0 0 2), and (1 0 1) dominant peaks. The particle size of nano ZnO powders was about 250 nm. The sensitivity of nano ZnO:Ni based sensors for 5 ppm CH4 gas and CH3CH2CH3 gas was measured at room temperature by comparing the resistance in air with that in target gases. The highest sensitivity of the ZnO:Ni sensor to CH4 gas and CH3CH2CH3 gas was observed at Ni 4 wt%. The response and recovery times of 4 wt% Ni coated ZnO:Ni gas sensors were 14 s and 15 s, respectively.

n-Pentane의 분리 및 회수를 위해 분리막의 제조가 용이하고 유기용매에 대한 내용매성이 있는 polyetherimide (PEI)를 지지체로 poly (dimethyl siloxane) (PDMS)를 코팅하여 중공사 복합막을 제조하였다. 제조된 기체 분리막의 특성을 알아보기 위하여 n-Pentane과 질소를 이용하여 공급농도와 stage cut의 변화에 따른 n-pentane과 질소의 투과도, permeate, retentate의 농도, 농축도, 회수율을 측정하였다. n-pentane과 질소의 투과도는 각각 2485.3, 9.9 GPU를 나타내었고, stage cut이 감소하고 공급농도가 증가할수록 투과측의 n-pentane 농도는 증가하는 경향을 나타내었다. 반면 회수효율의 경우에는 stage cut이 증가할수록 공급농도가 감소할수록 증가하는 경향을 나타내었다.

Co and Ni as catalysts in SnO2 sensors to improve the sensitivity for CH4 gas and CH3CH2CH3 gas were coated by a solution reduction method. SnO2 thick films were prepared by a screen-printing method onto Al2O3 substrates with an electrode. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a chamber. The structural properties of SnO2 with a rutile structure investigated by XRD showed a (110) dominant SnO2 peak. The particle size of the SnO2:Ni powders with Ni at 6 wt% was about 0.1 μm. The SnO2 particles were found to contain many pores according to a SEM analysis. The sensitivity of SnO2-based sensors was measured for 5 ppm of CH4 gas and CH3CH2CH3 gas at room temperature by comparing the resistance in air to that in the target gases. The results showed that the best sensitivity of SnO2:Ni and SnO2:Co sensors for CH4 gas and CH3CH2CH3 gas at room temperature was observed in SnO2:Ni sensors coated with 6 wt% Ni. The SnO2:Ni gas sensors showed good selectivity to CH4 gas. The response time and recovery time of the SnO2:Ni gas sensors for the CH4 and CH3CH2CH3 gases were 20 seconds and 9 seconds, respectively.

DeNOx experiments for the effects of hydrocarbon additives on diesel SNCR process were conducted under oxidizing diesel exhaust conditions. A diesel-fueled combustion system was set up to simulate the actual cylinder and head, exhaust pipe and combustion products, where the reducing agent NH3 and C2H6/diesel fuel additives were separately or simultaneously injected into the exhaust pipe, used as the SNCR flow reactor. A wide range of air/fuel ratios (A/F=20~40) were maintained, based on engine speeds where an initial NOx level was 530 ppm and the molar ratios (β=NH3/NOx) ranged between 1.0~2.0, together with adjusting the amounts of hydrocarbon additives. Temperature windows were normally formed in the range of 1200~1350K, which were shifted downwards by 50~100K with injecting C2H6/diesel fuel additives. About 50~68% NOx reduction was possible with the above molar ratios (β) at the optimum flow #1 (Tin=1260K). Injecting a small amount of C2H6 or diesel fuel (γ=hydrocarbon/NOx) gave the promising results, particularly in the lower exhaust temperatures, by contributing to the sufficient production of active radicals (OH/O/HO2/H) for NOx reduction. Unfortunately, the addition of hydrocarbons increased the concentrations of byproducts such as CO, UHC, N2O and NO2, and their emission levels are discussed. Among them, Injecting diesel fuel together with the primary reductant seems to be more encouraging for practical reason and could be suggested as an alternative SNCR DeNOx strategy under diesel exhaust systems, following further optimization of chemicals used for lower emission levels of byproducts.