Catalysis on evaporated metal films III. The efficiency of different metals for the reaction between ethane and deuterium

VACUUM

Classified A b s t r a c t s

I

--

General

Science

and Engineering Contd

~

I

dlfficultms an the m e a s u r e m e n t of the luminescence glow curve where a linear h e a t i n g rate is r e q m r e d and t e m p e r a t u r e e q m h b r m m is n o t achieved Somma*re Des expermnces faltes a~ec du p h o s p h o r e sont r a p p o r t e e s et les r6sultats o n t un m t e r 6 t dans le d o m a m e des p o u d r e s asolantes p o u r ~ide

Abs~ractiNo and References Letter b~ R tI Bube ~z R E bchladel Rev 5'ez Instr~ra 25, Sept 1954 921-922

A N e w Type of H e h u m L~quefier See A b s t r a c t No 169/II

245/i

A Lmde H e h u m Llquefier-Cryostat C o m b m a t m n Statable for Operatmn Down to I 3°K See A b s t r a c t No 170/II

246/I

The O r g a m s a t m n and Purpose of the L1qmd H e h u m Pool See A b s t r a c t No 6 9 / I V

247/I

A n Efficmnt Cryostat for Producing Temperature Between 4 ° and 8o°K The Productldn of Llqmd Hydrogen Targets Using Llqmd H e h u m See A b s t r a c t No 1 9 3 / I I I

248/I

0

I6 --

0

CHEMISTRY

--

i6

The Productmn of Radm-Isotopes See A b s t r a c t No 1 8 7 / I I I

249/I

M e a s u r e m e n t of T e m p e r a t u r e Dlstmbutmn in a Low-Pressure Flat F l a m e Umted States The t e m p e r a t u r e d l s t r l b u t m n m a v e r y lean, flat p r o p a n e - a i r flame was m e a s u r e d b y the thermocouple method, at a p r e s s u r e of 0 0594 a t m o s The t e m p e r a t u r e change occurred m a zone a b o u t 3 cm think Wall-quenching was mmamlsed b y ernploymg a b u r n e r t u b e d i a m e t e r of 25 cm The thermocouple w a s made from 1 2 - m m r o n wire, coated w i t h ceramic to avoid catMyhc effects One h u n d r e d e x p e r i m e n t a l t r a v e r s e p o i n t s were obtained, w i t h a s t a n d a r d d e v m t m n of ~ 0 016 cm The b u r n i n g veloclty was also measured, a n d was found to ~ a r y w i t h the reverse 0 30 p o w e r of p r e s s u r e Thin as m agreement w i t h E g e r t o n and Sen's result, obtained over a more h m l t e d range of pressure The t e m p e r a t u r e p a t t e r n was analysed m a t h e m a t m a l l y to obtain the p a t t e r n of h e a t release rate, t a k i n g into account the ~amatmn w i t h t e m p e r a t u r e of t h e r m a l conductlvatv and specific h e a t I t was found t h a t the h e a t release began at 300°C, attained a m a x i m u m value of 1 2 cal / c m a/see at 1,100°C, was nowhere negative, and was flmte over a zone a b o u t 2 cm think The m a x i m u m t e m p e r a t u r e of the flame w a s 1,332°C The result obtained for the ' l g m t m n p o i n t ' w a s found to be extremely senmtlve to the e x p o n e n t giving the t e m p e r a t u r e dependence of the t h e r m a l conductl~lty Some calculatmns relating to the chemlcM k m e t m s o1 the flame are described

250/I

(Sczence Abstracts) Sommazre On a mesur6 la distribution de t e m p 6 r a t u r e d ' u n e f l a m m e plate de p r o p a n e et d'mr, k la pressrun de 0 0594 a t m

ArtMe b) R Friedman & E Burke J Chem 2hys 22, May 1954 824-830

S e p a r a t m n of F l u o r a n t h e n e and Chrysene by Molecular Dlstfllatmn See A b s t r a c t No 1 8 2 / I I I

Catalyms on E v a p o r a t e d Metal Films III The Efficmncy of Different Metals for the Reachon Between Ethane and D e u t e r m m Umted Kzngdom The investigation reported here follows a previous investigation (Part II) p u b h s h e d in 1953 (Proc Roy Soc, 2x7A , 376) which dealt w i t h the reaction between d e u t e r i u m and m e t h a n e and was conducted w i t h the object of d e t e r m i n i n g the mltlal distribution of the v i n o u s r e a c t m n p r o d u c t s on a n u m b e r of metal catalysts and the activation energies and frequency factors of the reactions t o g e t h e r with the detaded k m e t m s The catalytm a p p a r a t u s employed an these e x p e r i m e n t s has been described m Proc Roy Soc, 214A , 1952, 413 A m a s s s p e c t r o m e t e r of special design was used to analyse the gas m i x t u r e s The m e t h o d used for depomtmn of the m e t a l films b y ~ a c u u m e v a p o r a t m n has been described in P a r t I of the serms of mvestagatmns Ormntat m n and ~tructure of the films deposited w a s e s t a b h s h e d b y e x a m m a t m n in the electron dfffractmn c a m e r a Tungsten, m o l y b d e n u m , t a n t a l u m , zarcomum, c h r o m m m , v a n a d m m , mckel, platinum, palladium, r h o d m m ,

October, 1954

Vacuum Vol I V No

252/I

516

4

VACUUM

Classified A b s t r a c t s

I --

General

Scmnce

and

Engineering

--

I

Abstract No and R e f e r e n c e s

Contd

r u t h e n i u m , m a n g a n e s e , sllxer, iron a n d c o b a l t fillns h a v e be e n s t u d i e d All films ~ e r e d e p o s i t e d a t (VC T h e r e a c t i o n vessel h a d a v o l u m e of 180 ml The gas m i x t u r e a d m i t t e d h a d a n e i ght -fol d excess of d e u t e r i u m (4fold for t u n g s t e n ) The e t h a n e c o m p o n e n t is s h o w n in t h e t a b l e be l ow The i n i t i a l d i s t r i b u t i o n s e s t a b l i s h e d

('ataly~t

A dmzttance Temperature

Tantalum, tool bd( num"L ruthenluln, 7nconlunl ff Tungsten Others

-78 C -78 C 0 (3

in th e e x p e r n n e n t are shown

In

Partial

l~t 2Vo of Ethane Moh

2 32 mm Hg 2 90 n u n Hg 2 5~ nmi Hg

1 80 < 10 ~ n:ol 2 25 / 10 TM tool 1 b4 . 10 t" tool

a t a b l e p a r t l y r e p r o d u c e d belo,~

Dzstr~butwns oJ Deuh~o-Ethanes fot

Ple~b~le

I n t h e case of m o l \ b d e n u m t h e m a i n p r o d u c t

Vamous Catalysts

D~t~ ~but~on t'utalq~t

O

d~

d~

d~

d~

d~ I

d.

I

Mob bdenum Chrommn: Palladmm

0 8l 0 47 0 05

0 14 0 18 0 0o

0 031) 0 0or) 0 080

0 007 0 000 0 11

0 0 072 0 19

0 0 15 0 52

w as C 2HsD, in t h e case of p a l l a a l u m C2D6 a n d m t h e case of c h r o m i u m b o t h were m a j o r p r o d u c t s "i he a c t i v a t i o n energ ies o b t a i n e d x ar:ed from 7 0 k c a l / m o l e for m o l y b d e n u m t o a m a x i m u m of 21 4 k c a l / m o l e for p a l l a d i u m H i g h f r e q u e n c y f a c t o r s were found to coincide ,Mth h i g h e ne rgi e s of actl~ a t l o n M a n g a n e s e a n d sllx er films w ere c o m p l e t e l y l n a c t l x e for e x c h a n g e a n d c r a c k i n g up to t e m p e r a t u r e s of 400~C I r o n w a s i n a c t i v e for t e m p e r a t u r e s u p to 370~C b u t showed, a t a b o u t t h e s e t e m p e r a t u r e s , a p r o n o u n c e d t e n d e n c y to c r a c k i n g Serious c r a c k i n g of e t h a n e occurred on n i c k e l films a b o v e 160°C The dmcusslon of t h e e x p e r i m e n t s l e a ds t o t h e dex e l o p m e n t of a t h e o r y for t h e l i k e l y m e c h a m s m a c c o u n t i n g for t h e d i s t r i b u t i o n The process s u g g e s t e d is c a l l e d ' r e p e a t e d second p o i n t ' a d s o r p t i o n p r o c e e d i n g in t h i s p a r t i c u l a r case via a d s o r b e d e t h y l e n e re s i due s The o u t c o m e of e x p e r i m e n t s on o r i e n t e d a n d u n o r l e n t e d n i c k e l films i n d i c a t e d t h a t t h e n a t u r e of t h e c r y s t a l faces h a d a n effect on t h e c a t a l y t i c a c t i v i t i e s of t h e film 5omma~}e L ' e f f i c a c l t e de dffferents m e t a u x d i n s la r e a c t i o n e n t r e l ' e t h a n e e t le d e u t e r i u m a ete e t u d m e c o m m e p a r t i e d ' u n e l m p o r t a n t e e t u d e sur les p e r f o r m a n c e s c a t a l ~ t i q u e s de films de m e t a u x ev apores Determmahon

of Momture

m Cereals

Revmw

of Methods

m Common

Use

A:ticle bx J R Andeison & C Kemball

Proe l~oy Aoc 2 2 3 A , Ma~, 1954

361-377

253, I

Umted Kzngdom

O

The m e t h o d s ax a l l a b l e for t h e d e t e r m m a h o n of t h e m o i s t u r e c o n t e n t in cereals are rex iexved No a b s o l u t e m e a s u r e m e n t s are possible, m a l n l 5 due to t h e d i f f i c u l t y of d e f l m n g t h e t e r m m o i s t u r e A s t a n d a r d d e f i n i t i o n w a s a t t e m p t e d b-~ Trolle ( J Inst B~ewzng, 194q, 354) as follows 'B~ m o i s t u r e shall be u n d e r s t o o d t h e loss in w e i g h t w h i c h t h e s u b s t a n c e u n d e r g o e s b5 e v a p o r a t i o n d u r i n g a rex ersible process of d r y i n g to p r a c t i c a l l y c o n s t a n t w e i ght , u n d e r such c o n d i t i o n s t h a t t h e s u b s t a n c e does n o t u n d e r g o d e t e c t a b l e a l t e r a t i o n of a n y s i gmfl c a nc e o t h e r t h a n t h e r e v e r s i b l e loss o£ toOlS ~urc ' I t IS difficult to fulfil t h e s e condatmns in r o u t i n e d e t e r m i n a t i o n s , a n d an practice, therefore, ~t ~s n e c e s s a r y to define m o m t u r e c o n t e n t i n t e r m s of t h e e x p e r i m e n t a l p r o c e d u r e e m p l o y e d to d e t e r m i n e at, z e t h e r e s u l t s of d i f f e r e n t m e t h o d s do n o t n e c e s s a r i l y agree T h e r e are p h y s i c a l a n d c h e m i c a l m e t h o d s P h y s i c a l m e t h o d s are (a) O~eJz d~wn¢ This m e t h o d is speedy, s i m p l e a n d gives r e p r o d u c i b l e r e s u l t s w h i c h are s u f f i c i e n t l y precise for m o s t c o m m e r c i a l p u r p o s e s Howexer, n o r m a l o p e r a t i o n a l t e m p e r a t u r e is a b o v e 100'C a n d in some m a t e r i a l s t h i s t e m p e r a t u r e l e a d s to c h e m i c a l b i n d i n g of t h e w a er a n d t h u s to low r e a d i n g s or, a l t e r n a t i ~ ely, d e c o m p o s i t i o n of t h e m a t e r i a l m a y be caused, v i e I d i n g v o l a t i l e d e c o m p o s i t i o n p r o d u c t s , p r o d u c i n g hi gh r e a d i n g s (b) D~yzng zn vacuo I n t h i s m e t h o d t h e t e m p e r a t u r e e m p l o y e d is g o v e r n e d b y t h e r e q u i r e m e n t t h a t t h e p a r t m l p r e s s u r e of t h e w a t e r in t h e gas p h a s e should be less t h a n the v a p o u r pre s s ure of t h e ,~ a t e r In t h e s a m p l e The h i g h e r t h e v a c u u m , t h e lower t h e t e m p e r a t u r e r e q u i r e d C h e m m a l d r y i n g a g e n t s e m p l o v e d in t h e process are l i s t e d in d e c r e a s i n g ord er of efflcienc~ as follows P h o s p h o r u s p e n t o x i d e , m a g u e s m m p e r c h l o r a t e , m a g n e s i u m p e r c h l o r a t e trlh'~ d rate, fused caustic p o t a s h , c a l c i u m bromide, c a l c i u m oxide, a n d c a l c m m chloridc The n o r m a l opera~,lonal p r e s s u r e s are a b o u t 5 m m H g i n one i n s t a n c e quo ~ed 0 1 m m H g ~ a s us e d I n t h a t case ma i z e grist ,~ as dri e d a t 38 C, t h e whole t e s t t a k i n g 340 hours The ease of d r y i n g c a n be i n c r e a s e d b y p a s s i n g a s t r e a m of n i t r o g e n t h r o u g h t h e sx s t e m Se~ eral w o r k e r s hax e r e p o r t e d t h a t d r w n g i n vacuo a t m o d e r a t e t e m p e r a t u r e s (e g 40~C ) :s more effective t h a n d r y i n g a t atmost)herIc p r e s s u r e a t 100~C (c) Dzstdlahon method ~Ihe s a m p l e is h e a t e d w i t h an excess of a l i q u i d i m m i s c i b l e xxl t h w a t e r a n d t h e c o n d e n s e d v a p o u r s are collected i n a g r a d u a t e d recei~ er, t h e v o l u m e of w a t e r is t h e n m e a s u r e d d i r e c t l ' ; The m e t h o d h a s t h e a d x a n t a g e t h a t a c o n s t a n t t e m p e r a t u r e , d e t e r m i n e d b~ t h e boiling p o i n t of l h e l I q m d used, can be m a i n t a i n e d i n d e f i n i t e l y The m o s t i m p o r t a n t c h e m i c a l m e t h o d m e n t i o n e d :s t h e I
Somma*re

Les m e t h o d e s de d e t e r m i n a t i o n dc la t e n e u r e n h u m i d l t 6 c o m m u n e m e n t e mpl oye e s , s ont rex races, afln d ' 6 t r e a p p h q u e e s a u x eereales

OcloLeJ, 1954

Vacuum Vol I V No

Altlcle b 5 A Bennett & J R Hudson

J Inst Brevu*g 6o, Jan-Feb 1954 29-34

517 4