Using spilled over hydrogen in NH3 synthesis over supported Ru catalysts

The role of spilled over hydrogen in ammonia synthesis reaction was monitored over Ru/SiO2, Ru/SBA15 and Ru/CNF using an in-situ DRIFTS cell reactor. Strongly bound hydrogen trapped on the metal and spilled over hydrogen trapped on the support due to a diffusion barrier remained on the surface after the overnight purge followed by hydrogen exposure over a reduced catalyst. When N-2 flow was introduced at room temperature, IR characteristic signals of NH3 were observed, indicating the formation of ammonia from hydrogen trapped on the surface. Total and weak hydrogen adsorption isotherms measured at different temperatures indicated that at low coverages spilled over hydrogen is trapped on the support in a kinetically metastable state. These results indicated the possibility of ammonia synthesis with the irreversibly bound hydrogen present on the support. A new hydrogen feeding strategy was proposed after a microkinetic model was used to estimate the rates in a plug flow reactor. An incremental hydrogen feeding strategy in the earlier phases of the reaction was proposed to eliminate hydrogen poisoning. The model predictions revealed that the alternative feeding strategy increased the rates by two orders of magnitude at the early stages of the reaction.


Coke Minimization in Dry Reforming of Methane by Ni Based Mesoporous Alumina Catalysts Synthesized Following Different Routes: Effects of W and Mg
ARBAĞ, HÜSEYİN; YAŞYERLİ, SENA; YAŞYERLİ, NAİL; Doğu, Timur; DOĞU, GÜLŞEN (Springer Science and Business Media LLC, 2013-12-01)
Ni based mesoporous alumina (MA) catalysts were synthesized by sol-gel (SGA) and hydrothermal (MA) methods, following impregnation and one-pot synthesis routes and catalytic performances of these materials were tested in dry reforming of methane. Results proved the importance of synthesis procedure of the MA supports on the activity and coke resistance of the synthesized materials, containing 16 % Ni. Among these catalysts, MA prepared by the sol-gel technique (Ni@SGA) showed the highest activity in dry ref...
Oxidative coupling of methane over NbO (p-type) and Nb2O5 (n-type) semiconductor materials
Erarslanoglu, Y; Onal, I; Doğu, Timur; Senkan, S (Springer Science and Business Media LLC, 1996-01-01)
Oxidative coupling of methane to higher hydrocarbons was investigated using two types of semiconductor catalysts, NbO (p-type) and Nb2O5 (n-type) at 1 atm pressure. The ratio of methane partial pressure to oxygen partial pressure was changed from 2 to 112 and the temperature was kept at 1023 K in the experiments conducted in a cofeed mode. The results indicated a strong correlation between C-2+ selectivity performance and the electronic properties of the catalyst in terms of p- vs. n-type conductivity. The ...
Selective oxidation of propylene to propylene oxide using combinatorial methodologies
Miyazaki, T; Ozturk, S; Onal, I; Senkan, S (Elsevier BV, 2003-06-30)
Direct oxidation of propylene by oxygen to propylene oxide (PO) has been studied through the application of the techniques of combinatorial catalysis. Catalytic materials containing single and binary metal components were prepared by impregnating standard gamma-Al2O3 pellets. In the first stage, 34 single component catalytic materials at three different metal loading levels were prepared and screened for PO activity and selectivity using array channel microreactors and mass spectrometry. Experiments were co...
Room Temperature Photocatalytic Oxidation of Carbon Monoxide Over Pd/TiO2-SiO2 Catalysts
Karakaş, Gürkan (Springer Science and Business Media LLC, 2013-12-01)
The photocatalytic oxidation of carbon monoxide over TiO2-SiO2 and Pd/TiO2-SiO2 catalysts was studied. The catalyst samples were synthesized by using sol-gel technique coupled with hydrothermal treatment and all samples were hydrothermally treated before calcination in air. The catalyst samples were characterized by XRD, BET and DRIFTS techniques. The photocatalytic activity of the samples was determined by using circulated batch photoreactor coupled with in line gas transmission FTIR cell charged with 2,00...
Zeolite framework stabilized nickel(0) nanoparticles: Active and long-lived catalyst for hydrogen generation from the hydrolysis of ammonia-borane and sodium borohydride
Zahmakiran, Mehmet; Ayvali, Tugce; Akbayrak, Serdar; Caliskan, Salim; Celik, Derya; Özkar, Saim (Elsevier BV, 2011-07-19)
Among the hydrogen storage materials, ammonia-borane and sodium borohydride appear to be promising candidates as they can release hydrogen on hydrolysis in aqueous solution under mild conditions. Here, we report the development of a cost-effective and highly active nickel(0) nanoparticles catalyst for the hydrolysis of ammonia-borane and sodium borohydride. Nickel(0) nanoparticles confined in zeolite framework were prepared by using our previously established procedure and characterized by ICP-OES, XRD, TEM...
Citation Formats
D. Üner, “Using spilled over hydrogen in NH3 synthesis over supported Ru catalysts,” CATALYSIS TODAY, pp. 49–57, 2016, Accessed: 00, 2020. [Online]. Available: