TPR investigations on the reducibility of Cu supported on Al2O3, zeolite Y and SAPO-5

✍ Scribed by Dang Lanh Hoang; Thi Thuy Hanh Dang; Jana Engeldinger; Matthias Schneider; Jörg Radnik; Manfred Richter; Andreas Martin

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 607 KB
• Volume: 184
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2011.05.042

✦ Synopsis

Reducibility of Cu supported on Al 2 O 3 , zeolite Y and silicoaluminophosphate SAPO-5 has been investigated in dependence on the Cu content using a method combining conventional temperature programmed reduction (TPR) by hydrogen with reoxidation in N 2 O followed by a second the so-called surface-TPR (s-TPR). The method enables discrimination and a quantitative estimation of the Cu oxidation states þ 2, þ 1 and 0. The quantitative results show that the initial oxidation state of Cu after calcination in air at 400 1C, independent on the nature of the support, is predominantly þ2. Cu 2 þ supported on Al 2 O 3 is quantitatively reduced by hydrogen to metallic Cu 0 . Comparing the TPR of the samples calcined in air and that of samples additionally pre-treated in argon reveals that in zeolite Y and SAPO-5 Cu 2 þ cations are stabilized as weakly and strongly forms. In both systems, strongly stabilized Cu 2 þ ions are not auto-reduced by pre-treatment in argon at 650 1C, but are reduced in hydrogen to form Cu þ . The weakly stabilized Cu 2 þ ions, in contrast, may be auto-reduced by pre-treatment in argon at 650 1C forming Cu þ but are reduced in hydrogen to metallic Cu 0 .