Catalytic decomposition of HCFC22 (CHClF2)

Li, Gong Liang; Ishihara, Takeshi; Yoshihiko, Moro Oka; Takita, Yusaku

doi:10.1016/0926-3373(96)90084-3

Cited by 31 publications

(4 citation statements)

References 7 publications

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“…In our previous study on AlPO 4 , the active sites for the decomposition of CFC-12 are considered to be acid sites. 9 Therefore, the low activity of metal sulfates containing alkaline earth cations can be attributed to weak acidities, and the low activities of these catalyst also support the prediction that the acidity of the catalyst is an important factor in determining the CFC-12 decomposition activity.…”

Section: Resultsmentioning

confidence: 73%

“…Although various methods such as plasma treatment or reaction in alkaline liquid have been proposed for the decomposition of CFCs, [2][3][4] catalytic decomposition methods have the advantages of mild reaction conditions, high reaction rates, continuous operation, and a simple and compact apparatus. Many catalysts and catalytic reactions have been proposed for the decomposition of CFCs [5][6][7][8][9] or Cl-containing compounds such as CCl 4 . 10 However, in the decomposition of CFCs, products usually contain the strong acid HF and/or HCl, and a significant deactivation of catalyst generally occurs.…”

Section: Introductionmentioning

confidence: 99%

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Metal Sulfate Catalyst for CCl₂F₂ Decomposition in the Presence of H₂O

Moriyama

Nishiguchi

Ishihara

et al. 2001

Ind. Eng. Chem. Res.

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Activities for the hydrolysis of CCl 2 F 2 (CFC-12) on various metal sulfates were investigated in this study. It was found that Zr(SO 4 ) 2 exhibits a high activity for CFC-12 decomposition and a high selectivity to CO 2 . On the other hand, the metal sulfates Al 2 (SO 4 ) 3 , La 2 (SO 4 ) 3 , Ce 2 (SO 4 ) 3 , and Cr 2 (SO 4 ) 3 were also active for the hydrolysis of CFC-12. However, the activities for CFC-12 decomposition of MnSO 4 , CoSO 4 , and MgSO 4 were low, and decomposition of CFC-12 hardly occurred on the metal sulfates CaSO 4 , SrSO 4 , and BaSO 4 . Among the investigated metal sulfates, Zr(SO 4 ) 2 was the most active, and the complete decomposition of CFC-12 was achieved at 598 K. The CFC-12 decomposition rate monotonically increased with increasing CFC-12 partial pressure. On the other hand, CFC-12 conversion became highest at an oxygen content of 18.9 mol % and a H 2 O content of 5 mol %. Therefore, the main reaction on Zr(SO 4 ) 2 for CFC-12 decomposition into CO 2 and HCl and HF is the hydrolysis reaction. The high activity to CFC-12 decomposition on Zr(SO 4 ) 2 was stably sustained over the 40-h period examined. Therefore, the metal sulfate Zr(SO 4 ) 2 is highly active for the hydrolysis of CFC-12 and has sufficient stability against fluorination and/or chlorination.

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Section: Resultsmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Metal Sulfate Catalyst for CCl₂F₂ Decomposition in the Presence of H₂O

Moriyama

Nishiguchi

Ishihara

et al. 2001

Ind. Eng. Chem. Res.

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“…On one hand, catalysts effective for the decomposition of halogen-containing compounds such as chlorofluorocarbons (CFCs), hydrofluorocarbons (HFC), and perfluorocarbons (PFC) have been studied by many researchers. A number of metal oxide catalysts including γ-Al 2 O 3 ; − SiO 2 −Al 2 O 3 ; TiO 2 −SiO 2 ; ZrO 2 −Cr 2 O 3 ; ZnO/γ-Al 2 O 3 , V 2 O 5 /γ-Al 2 O 3 , and Cr 2 O 3 /γ-Al 2 O 3 ; , WO 3 /Al 2 O 3 −ZrO 2 ; , WO 3 /M x O y (M = Ti, Sn, Fe); TiO 2 −ZrO 2 ; Al−metal oxides; mixed oxides of MnO−CuO; ZrO 2 /FeCl 3 /activated charcoal; , various zeolites including H−Y, ,− Na−Y, , H−mordenite, , Y−FAU, H−ZSM5, CsNaY−FAU, and supported noble metals; Au/Co 3 O 4 ; and Pt/TiO 2 −ZrO 2 mixed oxides were studied. Special catalysts such as CuO/CuSO 4 , , H 2 SO 4 /TiO 2 and H 2 SO 4 /TiO 2 −ZrO 2 , transition metal chloride promoted γ-Al 2 O 3 , and BPO 4 − are also reported.…”

Section: Introductionmentioning

confidence: 99%

“…Since HF and F 2 are strong acids and metal fluorides are more stable than the corresponding metals or metal oxides, metal or metal oxide catalysts are gradually transformed into the corresponding fluorides during the decomposition of fluorine-containing compounds. Metal fluorides are known as the catalysts for the synthesis of fluorine-containing hydrocarbons using HF. , The catalytic activity of metal fluorides does not seem to be very high, because the catalytic activity of metal oxides or zeolites decreased with reaction time. , However, that has not yet been reported.…”

Section: Introductionmentioning

confidence: 99%

Metal Phosphate Catalysts Effective for Degradation of Sulfur Hexafluoride

Kashiwagi

Takai

Takubo

et al. 2008

Ind. Eng. Chem. Res.

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SF6 decomposed stably over AlPO4, CePO4, YPO4, and Zr3(PO4)4 at 800−1000 K, but Ca2P2O7, Mg2P2O7, and Sr2P2O7 were less active. Active catalysts crystallized during the reaction. SO3, SO2F2, and HF were obtained as major products. SO3 was selectively formed over YPO4 and Zr3(PO4)4, but SO2F2 formed over AlPO4 and CePO4 in a significant selectivity at lower temperatures. Decomposition activity was independent of the concentration of oxygen, but it was dependent on the concentration of water vapor, suggesting that hydrolysis is the essential reaction. Catalytic activity was independent of the acidity of the catalysts. Catalytic activity was independent of the amount of surface hydroxyls, but it was correlated with the concentration of surface hydroxyls. From an analogy of hydrolysis of CCl2F2 on AlPO4, degradation may proceed via a similar bidentate surface intermediate, OsurfaceH···F(SF4)F···HOsurface, in which two fluorine atoms of SF6 interacted with two surface hydroxyls. AlPO4 showed a steady activity and high selectivity at 843 K for 25 h, suggesting a long catalyst life. AlF3 was significantly less active than metal phosphates. This suggests that development of the catalysts which are not transformed into metal fluorides is important.

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