Nanostructured surface

Isomerization of n-hexane over acid-modified nanosized nickel-containing natural zeolites
Patrylak L.K.1, Pertko O.P.1, Yakovenko A.V.1,  Voloshyna Yu.G.1, Povazhnyi V.A.1, Kurmach M.M.2
1 Department of Catalytic Synthesis, V.P Kukhar Institute of Bioorganic Chemistry and Petrochemistry of  NAS of Ukraine. Murmanska Str., 1, Kyiv-02094, Ukraine. 
E-mail:lkpg@ukr.net
2 Department of Porous Compounds and Materials, L.V.Pysarzhevski Institute of Physical Chemistry of NAS of Ukraine. Prospect Nauky, 33, Kyiv-03028 , Ukraine 

Scientists around the world are focusing the increasing attention on the creation of new nanostructured materials, among the last porous carbon and micro/mesoporous zeolite-containing materials are of great importance [1, 2]. 
The purpose of the work was the expansion of natural zeolite rock pores by acid treatment as well as nickel precipitation on the samples for obtaining the linear alkanes isomerization catalyst. The original material for modification was the mordenite-clinoptilolite rock (Lypcha, Transcarpation region). The natural rock was first grounded to a fraction of 0.5-1.0 mm, and then it was treated with ammonium chloride at 100 oC for 2-3 h and calcined (500 oC, 2 h). For pores expanding the rock was dealuminated by removing the structural aluminum from the zeolite lattice with hydrochloric acid (1, 3 and 5 mol/dm3) for 3 h at 100 oC. On the samples obtained the nickel has been precipitated (1, 1.5, 2, 3 wt %). 
Acid treatment increases the volume of mesopores with diameter of 2-10 nm by 2-3 times (BJH and DFT calculations) and micropores up to 4 times. The crystallite size of nickel deposited was estimated by TEM. The predominant spices are of 5-10 nm, but bigger ones up to 20-50 nm were found also. The samples were tested in n-hexane isomerization in a flow micro-pulse set-up in a hydrogen stream. The best performance was demonstrated by the sample with 2 % of Ni (i-C6 yield 20 % at 250 oC), which exceeds the results for microporous synthetic mordenite (13 % at 300 oC). Therefore, Ni-containing natural zeolites look promising as catalysts for alkanes isomerization.

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