• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2539-2545
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• 2012

In the present study, we suggest a new way to reactivate performance of direct formic acid fuel cell (DFAFC) and explain its mechanism by employing electrochemical analyses like chronoamperometry (CA) and cyclic voltammogram (CV). For the evaluation of DFAFC performance, palladium (Pd) and platinum (Pt) are used as anode and cathode catalysts, respectively, and are applied to a Nafion membrane by catalyst-coated membrane spraying. After long DFAFC operation performed at 0.2 and 0.4 V and then CV test, DFAFC performance is better than its initial performance. It is attributed to dissolution of anode Pd into $Pd^{2+}$. By characterizations like TEM, Z-potential, CV and electrochemical impedance spectroscopy, it is evaluated that such dissolved $Pd^{2+}$ ions lead to (1) increase in the electrochemically active surface by reduction in Pd particle size and its improved redistribution and (2) increment in the total oxidation charge by fast reaction rate of the Pd dissolution reaction.

• 대한의용생체공학회:의공학회지
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• 제22권6호
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• pp.511-518
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• 2001

치과용 고-Pd계 합금인 76.5wt.%Pd-11 6%Cu-7.2%Ga계 및 77.3%Pd-6.0%Ga계 합금의 주조. 탈개스 및 세라믹소성처리 후 부식저항성을 0.9%NaCl 및 Fusayama 전해액에서 동전위분극법을 이용하여 평가하였다. 미세조직의 변화에 따라 약간의 부식속도 차이를 나타내었으나 이는 미미하여 치과재료로서의 부식저항성은 문제가 없는 것으로 판단되었다 합금조성에 따른 부식저항성은 77.3%Pd-6.0%Ga계 합금이 76.5%Pd-11.6%Cu-7.2%Ga계 합금보다 우수한 것으로 나타났다. 이러한 결과는 76.5%Pd-11.6%Cu-7.2%Ga계 합금은 급냉조건과 Cu의 첨가로 공정반응을 촉진시켜 미세조직에 편석 및 석출물들이 존재했기 때문이었으며 77.3%Pd-6.0%Ga계 합금은 기지조직이 고용체로 구성되어 부식저항성 이 우수하였다.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.986-990
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• 2004

Condensation of salicylaldehyde $(2-HOC_6H_4C(O)H)$ with allylamine afforded the unsaturated salicylaldimine, $2-HOC_6H_4C(H)=NCH_2CH=CH_2$. Similar reactivity was observed with substituted salicylaldehydes. Further reaction of these Schiff bases with palladium acetate or $Na_2PdCl_4$ afforded complexes of the type $PdL_2$, where L = deprotonated Schiff base. The molecular structure of the parent salicylaldimine palladium complex $[trans-(2-OC_6H_4C(H)=NCH_2CH=CH_2)_2Pd]$ (1) was characterized by an X-ray diffraction study. Crystals of 1 were monoclinic, space group $P2_1/n,\;a\;=\;14.0005(9)\;{\AA},\;b\;=7.2964(5)\;{\AA},\;c\;=\;17.5103(12)\;{\AA},\;{\beta}\;=\;100.189(1)^{\circ}$, Z = 4. Analogous chemistry with 4-vinylaniline also gave novel palladium complexes containing a pendant styryl group. Crystals of $[trans-(2-HOC_6H_4C(H)=N-4-C_6H_4CH=CH_2)_2Pd]$ (4) were monoclinic, space group $P2_1/c$, a = 13.7710(14) ${\AA}$, b = 11.0348(11) ${\AA}$, c = 7.8192(8) ${\AA}$, ${\beta}\;=\;98.817(2)^{\circ}$, Z = 2.

• 공업화학
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• 제10권4호
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• pp.557-562
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• 1999

압축천연가스 자동차에서 배출되는 메탄의 산화를 위한 Pd 촉매의 특성을 조사하였다. 알루미나에 담지된 Pd 촉매와 La과 Ce의 조촉매가 첨가된 촉매들을 함침법으로 제조하였다. 메탄산화 반응은 U-튜브 흐름 반응기에서 공간속도(GHSV)가 $72000h^{-1}$이고 반응온도가 $200{\sim}800^{\circ}C$ 범위에서 실험을 수행하였다. 촉매는 XRD, XPS, BET 표면적 및 수소화학흡착 실험에 의하여 특성화되었다. $Pd/{\gamma}-Al_2O_3$ 촉매 제조시 전구체로 $Pd(NO_3)_2$를 사용하고 $600^{\circ}C$로 소성하였을 때 $CH_4$ 산화의 활성이 가장 높았다. 소성된 $Pd/{\gamma}-Al_2O_3$ 촉매에서 palladium은 대부분 PdO로 존재하였으며, 이것의 메탄 산화 반응 활성이 환원된 촉매에 대부분 존재하는 Pd 금속 보다 높았다. 넓은 범위의 redox ratio에서 실험을 반복하면 $Pd/{\gamma}-Al_2O_3$ 촉매의 활성이 감소하고 높은 활성을 보이는 window 영역이 좁아지는 특성을 보였다. 조촉매로 Ce가 첨가된 촉매는 오히려 메탄 산화 활성이 감소하였으며, 조촉매로 La 이 첨가된 $Pd/La/{\gamma}-Al_2O_3$ 촉매는 담체와 Palladium의 열적 안정성이 향상되어 $1000^{\circ}C$에서 aging된 후에도 우수한 활성을 보였다. 또한 $Pd/La/{\gamma}-Al_2O_3$ 촉매의 NO에 의한 $CH_4$ 제거 반응 특성에서 산소가 존재하지 않는 경우 redox ratio가 1.2 근처에서 메탄이 모두 제거되었으나 산소가 존재하면 메탄 제거율이 크게 감소하였다.

• Applied Microscopy
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• 제46권2호
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• pp.105-109
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• 2016

Palladium has been used as a catalyst not only in Suzuki and Heck cross coupling reaction in organic chemistry, but also in automobile industry for the reduction of vehicle exhausts. The catalytic activity of Pd nanoparticles depends strongly on their size and exposed crystalline facets. In this study, the single crystalline palladium nanocubes/nanorods were prepared in the presence of polyvinyl pyrrolidone (PVP) and potassium bromide (KBr) using the polyol method. Selected area diffraction pattern and high-resolution transmission electron microscopy (TEM) were performed by TEM. The result shows that the ratio of KBr/PVP is the key factor to determine whether the product is cubes or rods. The as-prepared Pd nanocubes were highly uniform in both size and shape. The ordered packing structures including monolayer and multilayer can be fabricated via the rate-controlled evaporation of solution solvent. The catalytic activity of these Pd nanocubes towards heck reaction of iodobenzene with acrylate or acrylic acid was found to be higher than that of Pd nanorods. We suspect it is caused by the difference of energy state while Pd nanocubes is {100} plane and nanorods is {111} plane.

• Bulletin of the Korean Chemical Society
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• 제18권11호
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• pp.1183-1185
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• 1997

Dimethylamine complexes of palladium(Ⅱ) [(PCP)Pd(NHMe2)](OTf) (PCP = 2,6-(R2PCH2)2C6H3); R = Ph (1), R = Cy (2)), have been prepared from the reaction of (PCP)Pd(OTf) and dimethylamine. The complex 1 is stable both in solution and in the solid state, while 2 is stable only in solution in the presence of dimethylamine although the formation of 2 in solution is quantitative by NMR Spectroscopy. A solution NMR spectroscopic study shows that dimethylamine favors over carbon monoxide in the coordination sphere of palladium(Ⅱ) having rigid terdentate ligands. The complexes 1 and 2 in chlorinated solvents undergo a chlorine abstract reaction yielding Pd(2,6-(R2PCH2)2C6H3)Cl in the presence of a base such as dimethylamine and DABCO (diazabicyclooctane), in which a transient dimethylamido palladium(Ⅱ) species likely involves.

• Macromolecular Research
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• 제17권3호
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• pp.144-148
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• 2009

Poly(1-oxo-2-phenyltrimethylene) was synthesized by palladium-catalyzed copolymerization of styrene and carbon monoxide in quaternary ammonium ionic liquids. The $[Pd(bipy)_2][PF_6]_2$ compound had relatively more catalytic activity than $[Pd(bipy)_2][BF_4]_2$ in ionic liquids. The catalytic activity of palladium (II) composite catalyst was superior to the catalyst formed in situ from palladium acetate, 2,2-bipyridyl, and $X^-$ ($X^-=PF_6^-$, $BF_4^-$) in ionic liquids. The effects of the volume of ionic liquids, reaction time and benzoquinone content on the copolymerization were also described.

• Mass Spectrometry Letters
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• 제14권3호
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• pp.110-115
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• 2023

The reaction of (COD)PdCl₂ with new C₃-symmetric tridentate L (COD = 1,5-cyclooctadien; L = 1,3,5-tris(picolinoyloxyethyl)cyanurate) in a mixture of acetone and dichloromethane produces single crystals consisting of unprecedented monometallacyclic [PdCl₂(L)]. This cyclic compound arises from trans-chelation of two of three donating pyridyl groups of L, while the third pyridyl group remains uncoordinated. Electrospray ionization mass spectrometry (ESI-MS) data on L exhibited the major peak corresponding to [C₂₇H₂₄N₆O₉ + H⁺]⁺. Fast atom bombardment mass spectrometry (FABMS) data on [PdCl₂(L)], however, showed the mass peak corresponding to the L instead of the present palladium(II) compound species, due to the insolubility and dissociation in solution. The physicochemical properties of the present palladium(II) compound were fully characterized by means of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, thermal analysis, single-crystal X-ray diffraction (SC-XRD) measurement.

• 대한화학회지
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• 제37권4호
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• pp.423-430
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• 1993

$trans-PdEt_2(PMe_3)_2$와 styrene을 반응시켜 얻어진 $Pd(PMe_3)_2$(styrene)에 methacrylic acid와 trans-crotonic acid를 각각 반응시켜 새로운 팔라듐(O)-올레핀착물로서 $(PMe_3)_2Pd{CH_2=C(CH_3)COOH}$와 (PMe_3)_2Pd{(CH_3)CH=CHCOOH}$를 합성하고, 구조와 특성을 원소분석, IR 및 $^1H-,\;^{13}C-,\;^{31}P-NMR$ 등의 분광학적 방법으로 조사하였다. methacrylic acid 와 trans-crotonic acid에 존재하는 올레핀의 이중결합은 팔라듐(O)에 ${\pi}$-결합을 형성하였고, 카르복실산은 팔라듐에 결합되지 않았음을 알게되었다. 그리고 동일한 반응에서 metallacycle을 형성하는 3-butenoic acid와 비교 검토하였다.

• 분석과학
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• 제36권4호
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• pp.198-203
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• 2023

The reaction of cis-protected (Me4en)Pd(II) species with potentially multidentate bis(benzylthio)methylenepropanedioate (L) was carried out to obtain a monometallic compound, [(Me₄en)Pd(L)], in O,O'-coordination mode. The bis(benzylthio)methylene group was bent strikingly from the palladium square plane at the dihedral angle of 70.40°. The physicochemical properties of the present palladium(II) compound were fully characterized by means of infrared and nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction measurement.