http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Praserthdam, Piyasan,Chaisuk, Choowong,Mongkhonsi, Tharathon 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.1
The catalytic activity behavior for the selective catalytic reduction of NO by C_3H_6 under excess oxygen and the nature of surface species on the active sites of Pt/AI_2O_3 catalyst after adding a second metal(Fe, Sn, Co, Cr or W)were investigated. It has been found that an important role of second metals is on TONs of C_3H_6 and NO conversions and the nature of surface species produced on the catalyst surface at low temperature instead of the catalytic activity behavior towards the temperature programmed reaction. Although the introduction of each second metal distinctly disturbs the characteristic of surface species, the reaction mechanism is presumably similar. The observation of few surface species and the investigation about their reactivity indicate that few mechanisms are simultaneously proceeding at the same reaction condition.
Piyasan Praserthdam,Narongrat Poovarawan,Thidaya Thitiapichart,Kongkiat Suriye,Joongjai Panpranot,Wimonrat Limsangkass,Francisco José Cadete Santos Aires 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.1
Lanthanum (0.5, 0.6, 0.75, 0.9 and 1 wt%) was added as a second metal on the 9 wt% WO3/SiO2 catalysts by the incipient wetness impregnation method. The catalysts were tested in the metathesis reaction of ethylene and 2- butene using either pure 2% trans-2-butene and the mixture of 1% cis- and 1% trans-2-butene as the reaction feed and were characterized by X-ray diffraction (XRD), nitrogen physisorption (BET), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy, ion-exchange titration, FT-Raman, ammonia temperature programmed desorption (NH3-TPD) and reactant temperature programmed desorption (reactant-TPD). An optimum lanthanum loading at 0.5 wt% could improve dispersion of tungsten active phase and adsorption properties of the reactants on the catalysts. The adsorption of the mixed cis/trans-2-butene isomer was much improved on the La- WO3/SiO2 catalysts with 0.5 wt% La.
Influence of Fe or Zn Loading Method on Toluene Methylation over MFI - Type Zeolite Catalysts
Phatansari, Suphot,Praserthdam, Piyasan,Punsupsawat, Thana 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.4
Toluene methylation with methanol was investigated on MFI-type zeolite catalysts containing Fe or Zn within the range of 0-2% by weight as an active component. The catalytic performances were compared on catalysts to which Fe or Zn was introduced by different methods, i.e., ion-exchanged and incorporation methods. The prepared catalysts were characterized by XRD, XRF, BET, FTIR and pyridine adsorption technique on in-situ FTIR. The results showed that the incorporated samples, H-Fe, Al-silicate (Si/Fe=150) and H-Zn, Al-silicate (Si/Zn=150), exhibited catalytic activity and xylene selectivities approximately equivalent to those from the ion-exchanged samples, Fe(0.8)/H-MFI and Zn(1.0)/H-MFI, containing nearly the same amount of Fe or Zn. The higher p-xylene selectivity was achieved with H-Fe, Al-silicate (Si/Fe=150) and H-Zn, Al-silicate (Si/Zn=150) because of Bro¨nsted acid strengths weaker than Fe(0.8)/H-MFI and Zn(1.0)/H-MFI. Therefore, the isomerization of p-isomer produced primarily was suppressed on the incorporated catalysts better than the ion-exchanged ones.
Solvent effect on synthesis of zirconia support for tungstated zirconia catalysts
Peangpit Wongmaneenil,Piyasan Praserthdam,Bunjerd Jongsomjit 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.2
Solvothermal reaction of zirconium n-butoxide (ZNB) in different solvent media, such as 1,3-pentanediol, 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol resulted in the formation of zirconium dioxide (ZrO2) nanostructure. Then, the 15%W/ZrO2 (WZ) catalysts using different zirconia supports were prepared by impregnationmethod. The effects of solvent on preparation of zirconia on the catalytic performance of WZ catalysts in esterification of acetic acid and methanol at 60 8C were investigated. The experimental results showed that ZrO2 particles prepared in 1,4-butanediol (ZrO2-BG) have a spherical shape, while in other glycols the samples were irregularly-shaped particles. The reaction results of esterification illustrated that the W/ZrO2-BG catalysts had high surface acidity and showed high acetic acid conversion. The W/ZrO2-PeG catalysts (ZrO2 particles prepared in 1,5-pentanediol, PeG) exhibited the lowest surface acidity among other samples due to strong interaction of proton species and the zirconia supports as proven by TGA. One of the possible reasons can be attributed to different amounts of carbon residue on the surface of catalysts.
LLDPE synthesis via SiO2–Ga-supported zirconocene/MMAO catalyst
Mingkwan Wannaborworn,Piyasan Praserthdam,Bunjerd Jongsomjit 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1
In this present study, the linear low-density polyethylene (LLDPE) was synthesized via ethylene/1-octene copolymerization with the zirconocene/MMAO catalyst by in situ impregnation of different silica (SiO2) supports. The SiO2 supports used were small-pored (SP) and large-pored (LP) sizes with and without Ga modification. It was found that the SP-SiO2 support exhibited higher polymerization activity (1.5 times) than that obtained from the LP-SiO2 one. This can be attributed to the lower amount of MMAO being present inside the SP-SiO2 support resulting in higher content of MMAO at the external surface. The higher activity in ethylene/1-octene copolymerization was also found with the supported catalyst having Ga modification onto both SP-and LP-SiO2 supports. The results demonstrated that the introduction of Ga may improve ability of supports to immobilize metallocene catalyst. Based on 13C NMR measurement, it indicated that all synthesized polymers were typical LLDPE having random distribution of comonomer.
Aromatization of Light Paraffins over Ga-containing MFI - type Catalyst
Phatansari, Suphot,Praserthdam, Piyasan,Sripusitto, Apisit 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.4
Aromatization of light paraffins such as propane and butane was investigated on MFI-type catalysts containing Ga as an active component. Even with less amount of Ga loading, Ga ion-exchanged MFI exhibited higher selectivity for aromatics, mainly benzene, toluene and xylene (BTX), than that of H-Ga-Silicate. This may be attributed to the presence of Al in Ga ion-exchanged MFI which increases the catalyst acidity. Further development was done by preparing H-Ga, Al-bimetallosilicate with the purpose of minimizing the catalyst preparation procedure. It has been found that H-Ga, Al-bimetallosilicate having Si/Ga ratio of 155 and Si/Al ratio of 40 exerted considerably high selectivity for aromatics, ca. 64% for BTX. This selectivity was comparable to that of H-Ga ion-exchanged MFI with the same amount of Ga loading. However, the bimetallosilicate catalyst can be prepared in only one step crystallization, which minimizes the catalyst preparation procedure.
Mongkhonsi, Tharathon,Praserthdam, Piyasan,Srihiranpullop, Sunee 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.5
The effect of K addition on the amount and dispersion of carbon deposition on metal sites and support sites was investigated on a physical mixture for hexane dehydrogenation. TPO, BET and ESR experiments were used for characterization. The K addition significantly decreases catalyst deactivation involving the amount of coke deposits and the density of carbon radicals on the metal and support sites because of ensemble and electronic effects, especially on the metal sites. Coke on the metal sites associated with carbonaceous species rich in hydrogen is less polymerized than coke on the support sites, corresponding to a more graphitic-like carbon.
Srihiranpullop, Sunee,Praserthdam, Piyasan 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.6
The main goal of this contribution was to study the probability of chain growth of coke on metal sites and on support sites for hexane dehydrogenation. The coke structure of the catalysts examined by IR was found to have the aromatic structure. Soxhlet extraction coupled with GC-14B(DB1 column) analysis was mainly employed for coke composition analysis and determination of the probability of chain growth (alpha value). It was found that the soluble coke was mainly composed of C_(8)-C_(12) on both sites. Interestingly, the probabilities of chain growth on both sites were identical. However, the extracted coke on the metal site was more easily removable and had lower carbon numbers than that on the support site. Moreover, the addition of promoter, especially of K promoter, was sensitive to inhibit the probability of chain growth, resulting in the reduction of the amount of coke.