The hydrogenation of methyl on metallic surfaces |
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Authors: | A E Gorodetskii R Kh Zalavutdinov V L Bukhovets S P Vnukov A P Zakharov |
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Institution: | (1) Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 117071, Russia |
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Abstract: | The stream technique was used to comparatively analyze the characteristics of the deposition of a-C:H films from methyl radicals
transferred by a carrier gas CH4/C2H
y
/H2 (y = 2, 4, 6) in a quartz tube with cylindrical insets made of Cu, Ni, Fe, W, Si, and stainless steel (SS), initial and coated
with thin Pd or Rh films, over the temperature range 300–1000 K. The deposition of methyl was fully suppressed in a tube section
heated to 380–800 K with all the insets specified. During further mixture movement outside this section in the tube with a
decreasing wall temperature, carbon deposition resumed. The most effective catalyst of the hydrogenation reaction was stainless
steel. Radicals and unsaturated hydrocarbons capable of polymerization at 300–400 K were fully removed from the carrier gas
flow (CH4/C2H
y
/H2) after several hundreds of collisions with the surface of SS heated to 420–470 K. The possibility of creating an SS recombination
filter for hydrocarbon radicals (the performance of radical hydrogenation reactions) transferred by a CH4/C2H
y
/H2 laminar flow was demonstrated. The deposition of a thin Pd film (∼10 nm) on steel did not increase the effectiveness of the
surface with respect to radical recombination reactions. At the same time, Rh films increased the catalytic effectiveness
of the surface of SS with respect to the hydrogenation of methyl and unsaturated hydrocarbons (380–420 K). The data obtained
were used to select temperature conditions and mutual arrangement for the construction elements of an ITER diverter made of
tungsten and stainless steel. |
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Keywords: | |
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