• Environmental Engineering Research
• /
• 제24권2호
• /
• pp.324-330
• /
• 2019

To recycle raw fly ash (RFA), a waste from thermal power plants, it was used to prepare solid catalysts which have many advantages compared with homogenous catalysts. When biodiesel was produced from soybean oil using RFA, only 1.2% of biodiesel conversion was obtained. A metal hydroxide, NaOH, KOH or $Ca(OH)_2$, was mixed with the acid-treated fly ash (ATFA), and the mixture was calcined at $700^{\circ}C$ for 3 h to prepare the solid catalyst. The solid catalyst prepared by mixing ATFA with NaOH, designated as SC-Na, showed a better performance than those prepared by mixing ATFA with KOH or $Ca(OH)_2$, respectively. The optimal mass ratio of ATFA with NaOH was 1:3, at which the proportion of $Na_2O$ increased to 60.2% in SC-Na, and 97.8% of biodiesel conversion was achieved under optimal reaction conditions (2 w% SC-Na relative to oil and 5 mL-methanol/g-oil at $50^{\circ}C$ for 4 h). Finally, a batch operation was repeatedly carried out to test the feasibility of reusing the solid catalyst, and more than 96% biodiesel conversion was stably achieved for the third round of operations. This study shows that RFA was successfully recycled to solid catalysts through a simple preparation method, and the solid catalyst was reused for the production of biodiesel with high conversion.

• Bulletin of the Korean Chemical Society
• /
• 제19권4호
• /
• pp.466-470
• /
• 1998

Catalytic hydrogenation of carbon dioxide for the simultaneous synthesis of methanol and dimethyl ether (together called oxygenates) over a combination of methanol synthesis and methanol dehydration catalysts has been studied. Various methanol synthesis and methanol dehydration catalysts were examined for this reaction. The addition of promotors like $Ga_2O_3\; and\; Cr_2O_3$ to Cu/ZnO catalyst gave much more enhanced yield on the formation of oxygenates. From the results, the promotional effect of $Cr_2O_3$ has been explained in terms of increase in the intrinsic activity of Cu while that of $Ga_2O_3$ being increase in the dispersion of Cu. Among the methanol dehydration catalysts examined, the solid acids bearing high population of intermediate-strength acid sites were found to be very effective for the production of oxygenates. HY zeolite which contains strong acid sites produce small amount of hydrocarbons as by-products. However, CuNaY zeolite in which the presence of strong acid sites are minimum gives very high oxygenates yield without the formation of hydrocarbons.

• 공업화학
• /
• 제3권1호
• /
• pp.7-17
• /
• 1992

100% $H_2SO_4$($H_0=-11.93$)보다 더 강한 산을 초강산이라고 한다. 그러나 고체초강산 촉매는 액체초강산촉매에 비하여 촉매와 반응생성물의 분리의 용이성, 촉매의 반복사용가능, 촉매의 재생가능 등과 같은 많은 이점을 가지고 있다. 이 총설에서는 고체초강산 촉매의 종류, 제법, 그리고 화학반응에서의 응용에 대하여 소개한다.

• 한국세라믹학회지
• /
• 제52권5호
• /
• pp.350-355
• /
• 2015

To develop ceramic composite anodes of solid oxide fuel cells without metal catalysts, a small amount of barium carbonate was added to an $(La_{0.8}Sr_{0.2})(Cr_{0.5}Mn_{0.5})O_3(LSCM)$ - YSZ ceramic composite anode and its catalytic effects on the electrode performance were investigated. A barium precursor solution with citric acid was used to synthesize the barium carbonate during ignition, while a barium precursor solution without citric acid was used to create hydrated barium hydroxide. The addition of barium carbonate to the ceramic composite anode caused stable fuel cell performance at 1073 K; this performance was higher than that of a fuel cell with $CeO_2$ catalyst; however, the addition of hydrated barium hydroxide to the ceramic composite anode caused poor stability of the fuel cell performance.

• 공업화학
• /
• 제31권4호
• /
• pp.383-389
• /
• 2020

프로필 술폰산으로 개질된 메조기공 실리카 고체 산 촉매를 octamethylcyclotetrasiloxane (D₄)의 양이온 개환중합을 위해 합성하였다. 서로 다른 기공 크기를 갖는 두 세트의 MCM-41 (1.7 및 2.8 nm) 및 SBA-15 (8.1 및 15.9 nm)을 촉매의 지지체로 사용하였고, 이를 (3-mercaptopropyl)trimethoxysilane으로 표면개질하고 산화시켜 술폰산으로 개질된 고체 산촉매를 제조하였다. 제조된 촉매는 기공 크기와 비표면적, 기공 부피가 약간씩 감소하였음을 X선 회절, 질소흡탈착을 통하여 확인하였다. 또한 적외선분광법과 핵자기공명법의 분광학적 방법을 이용하여 술폰산이 개질되었음을 확인하였다. 입도의 촉매 활성에 대한 효과를 관찰하기 위하여 주사전자현미경으로 관찰하였다. D₄의 개환중합을 통한 PDMS 합성을 위하여 촉매를 사용하였으며, 중합 반응의 전환율과 중합 속도는 촉매의 기공 크기, 비표면적, 입자크기 및 입자의 응집도에 의존하였다. 중합 속도의 순서는 8.1 nm의 SBA-15으로 제조한 촉매가 가장 반응속도가 빨랐으며, 가장 좋은 촉매 활성을 보였다.

• Bulletin of the Korean Chemical Society
• /
• 제32권1호
• /
• pp.225-228
• /
• 2011

Poly(4-vinylpyridine)-supported $Br{\phi}nsted$ acids (P4VP-HX) were prepared by wet impregnation technique. These supported acids were found as efficient heterogeneous green catalysts for acetylation of alcohol, amine and phenol with different catalytic activities. The wide application of P4VP-HX as reusable solid acid catalyst in organic reactions is possible because of its simple preparation and handling, stability, simple work up procedure.

• 공업화학
• /
• 제9권3호
• /
• pp.372-376
• /
• 1998

Pd를 지지체에 담지시킨 촉매($Pd/AlF_3$, $Pd/{\gamma}-Al_2O_3$)와 고체산촉매(${\gamma}-Al_2O_3$, ${\alpha}-Al_2O_3$, $AlF_3$)를 제조한 후 수소분위기에서 HCFC-142b(1-chloro-1,1-difluoroethane)의 탈염소반응을 수행하여 반응온도, 수소/HCFC-142b의 공급비(r) 및 Pd담지량 변화가 HFC-143a(1,1,1-trifluoroethane)와 HFC-152a(1,1-difluoroethane)로의 선택도에 미치는 영향을 조사하였다. 실험결과 $Pd/AlF_3$와 $Pd/{\gamma}-Al_2O_3$촉매에 의한 전환율은 각각 60%와 92%였고, 생성가스 중에서 HFC-143a로의 선택도는 각각 58%와 64%였다. 이때 최적반응조건은 반응온도, $200^{\circ}C$, 공간시간 1.05s, 수소/HCFC-142b의 공급비가 3이었다. 한편, 동일 조건하에서 ${\gamma}-Al_2O_3$와 ${\alpha}-Al_2O_3$, 그리고 $AlF_3$촉매에 의한 HCFC-142b의 생성가스로의 전환율은 각각 12%, 8%와 7%였고, 생성가스중 HFC-152a로의 선택도는 각각 94%, 92%와 90%였다.

• 공업화학
• /
• 제22권6호
• /
• pp.587-593
• /
• 2011

대기환경 규제와 자동차 성능 유지 등 고급 가솔린인 알킬레이트 생산공정에 대한 관심이 높아지고 있다. 알킬레이트는 이소부탄과 올레핀의 알킬레이션 반응을 통해서 생산된다. 하지만 기존의 공정에서 사용되고 있는 불산이나 황산의 유해성으로 인하여 새로운 친환경 촉매에 대한 연구가 활발히 진행되고 있다. 최근 기존의 고체산 촉매인 제올라이트 이외에 메조기공 촉매 및 이온성액체를 이용한 연구가 수행되고 있다. 본 논문에서는 이소부탄 알킬레이션 공정을 위한 친환경 촉매에 대한 논하려 한다.

• Bulletin of the Korean Chemical Society
• /
• 제28권12호
• /
• pp.2459-2465
• /
• 2007

V2O5/TiO2-ZrO2 catalyst modified with V2O5 was prepared by adding Ti(OH)4-Zr(OH)4 powder into an aqueous solution of ammonium metavanadate followed by drying and calcining at high temperatures. The characterization of prepared catalysts was performed using XRD, DSC, solid-state 51V NMR, and FTIR. In the case of calcination temperature of 500 oC, for the catalysts containing low loading V2O5 below 25 wt % vanadium oxide was in a highly dispersed state, while for catalysts containing high loading V2O5 equal to or above 25 wt % vanadium oxide was well crystallized due to the V2O5 loading exceeding the formation of monolayer on the surface of TiO2-ZrO2. The strong acid sites were formed through the bonding between dispersed V2O5 and TiO2-ZrO2. The larger the dispersed V2O5 amount, the higher both the acidity and catalytic activities for acid catalysis.

• Bulletin of the Korean Chemical Society
• /
• 제34권5호
• /
• pp.1481-1486
• /
• 2013

Bifunctional Fe-SBA-15-$SO_3H$ mesoporous materials with different Si/Fe molar ratios (3, 5, and 7) have been synthesized via a simple direct hydrothermal method and characterized by XRD, $N_2$-adsorption/desorption, TG/DTG and FT-IR techniques, and used as solid acid catalysts in the esterification of lactic acid with methanol. XRD and $N_2$ sorption characterizations show successful iron doping within the mesoporous channels of SBA-15-$SO_3H$. The FT-IR and TG/DTG characterizations also reveal the presence of iron. With the incorporation of Fe ions into the SBA-15-$SO_3H$, the acid sites substantially increased because of the self-separated acidity of the hydrolysis of $Fe^{3+}$ solutions. However, in the Si/Fe = 3 molar ratio, the catalytic conversion decreased which is caused by the reduced cooperation effect between the acid pairs due to the weakened hydrogen bonds and collapse of the pore structure. This further suggests that the mesoporous structure decreases with the decrease in Si/Fe ratio.