Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terep...Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation（λ>450 nm） from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO2 while the conversion was 90% and the complete mineralization was achieved over Pt-Pt 4+/TiO2 at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.展开更多
研究了以Pt-Cu-S/C作催化剂,3-氯-4-氟硝基苯常压加氢制备3-氯-4-氟苯胺的方法,考察了该催化剂对3-氯-4-氟硝基苯的催化加氢反应的性能,探讨了影响加氢反应的主要因素。实验表明,催化剂具有较高的催化活性和选择性。当催化剂中Pt的质量...研究了以Pt-Cu-S/C作催化剂,3-氯-4-氟硝基苯常压加氢制备3-氯-4-氟苯胺的方法,考察了该催化剂对3-氯-4-氟硝基苯的催化加氢反应的性能,探讨了影响加氢反应的主要因素。实验表明,催化剂具有较高的催化活性和选择性。当催化剂中Pt的质量分数为1%,Cu的质量分数为0.1%,S的质量分数为0.03%,催化剂用量为硝基物质量的0.5%,溶剂用量2 m L甲醇/1 g硝基物,反应温度80℃,压力为1.5 MPa时,3-氯-4-氟苯胺的产率为98%,纯度达99.5%以上。展开更多
以高硅(n(Si O2)/n(Al2O3)=373)HZSM-5分子筛为母体,采用浸渍法制备了一系列NH4F/Pt复合改性催化剂(w2)Pt-(w1)F-ZSM-5,以4-甲基联苯(4-MBP)与甲醇的烷基化为探针反应,考察了NH4F用量、Pt用量、NH4F改性后盐酸洗涤以及向反应体系添加水...以高硅(n(Si O2)/n(Al2O3)=373)HZSM-5分子筛为母体,采用浸渍法制备了一系列NH4F/Pt复合改性催化剂(w2)Pt-(w1)F-ZSM-5,以4-甲基联苯(4-MBP)与甲醇的烷基化为探针反应,考察了NH4F用量、Pt用量、NH4F改性后盐酸洗涤以及向反应体系添加水蒸气对反应的影响。结果表明,经复合改性后,0.75Pt-HCl-5F-ZSM-5催化剂用于4-MBP甲基化反应,其稳定性及二甲基联苯(DMBPs)的产率得到明显提高,反应2 h DMBPs产率为9.6%,反应20 h后,4-MBP转化率为9.1%,4,4’-DMBP选择性可达76.1%。而未改性HZSM-5催化剂上,反应2 h DMBPs产率为4.2%。向反应体系添加水蒸气可进一步提高(w2)Pt-(w1)F-ZSM-5催化剂的稳定性和4,4’-DMBP选择性,反应30 h 4,4’-DMBP选择性仍高达90%。展开更多
文摘Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation（λ>450 nm） from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO2 while the conversion was 90% and the complete mineralization was achieved over Pt-Pt 4+/TiO2 at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.
文摘研究了以Pt-Cu-S/C作催化剂,3-氯-4-氟硝基苯常压加氢制备3-氯-4-氟苯胺的方法,考察了该催化剂对3-氯-4-氟硝基苯的催化加氢反应的性能,探讨了影响加氢反应的主要因素。实验表明,催化剂具有较高的催化活性和选择性。当催化剂中Pt的质量分数为1%,Cu的质量分数为0.1%,S的质量分数为0.03%,催化剂用量为硝基物质量的0.5%,溶剂用量2 m L甲醇/1 g硝基物,反应温度80℃,压力为1.5 MPa时,3-氯-4-氟苯胺的产率为98%,纯度达99.5%以上。
文摘以高硅(n(Si O2)/n(Al2O3)=373)HZSM-5分子筛为母体,采用浸渍法制备了一系列NH4F/Pt复合改性催化剂(w2)Pt-(w1)F-ZSM-5,以4-甲基联苯(4-MBP)与甲醇的烷基化为探针反应,考察了NH4F用量、Pt用量、NH4F改性后盐酸洗涤以及向反应体系添加水蒸气对反应的影响。结果表明,经复合改性后,0.75Pt-HCl-5F-ZSM-5催化剂用于4-MBP甲基化反应,其稳定性及二甲基联苯(DMBPs)的产率得到明显提高,反应2 h DMBPs产率为9.6%,反应20 h后,4-MBP转化率为9.1%,4,4’-DMBP选择性可达76.1%。而未改性HZSM-5催化剂上,反应2 h DMBPs产率为4.2%。向反应体系添加水蒸气可进一步提高(w2)Pt-(w1)F-ZSM-5催化剂的稳定性和4,4’-DMBP选择性,反应30 h 4,4’-DMBP选择性仍高达90%。
