摘要:

AbstractWhen chromic acid solutions are passed through hydroxide‐form anion‐exchange resin columns, the resin is converted successively to the chromate and dichromate forms, the completion of the second process coinciding with the first appearance of chromic acid in the effluent. Continuation of the process beyond the breakthrough point results in the uptake of tri‐ and tetra‐chromate in proportions dependent on the concentration of the input solution. The polychromates are removed by means of water, and the dichromate by direct reaction with alkali, neither of these being ion‐exchange processes. Chromate is removed by exchange with hydroxide in the norm

ISSN:0021-8871    

DOI:10.1002/jctb.5010110701

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe gaseous oxidation of isopropyl alcohol has been studied in a flow system at temperatures between 350° and 450° at atmospheric pressure. Chemical analyses of the products have been made and the effects of temperature, reactant composition and surface conditions are recorded, particularly with reference to the formation and recovery of hydrogen peroxide.During the initial stages of the reaction, hydrogen peroxide and acetone are formed slowly in a linear chain cycle. This cycle continues throughout the reaction, but a small proportion of the alcohol apparently reacts in a different way, leading to the formation of acetaldehyde and formaldehyde. The reaction subsequently becomes autocatalytic in nature, and a complexity of C1and C2products is formed.The optimum conditions for the formation and recovery of high yields of hydrogen peroxide are discussed. The use of an ‘aged’ Pyrex vessel of low surface to volume ratio appears to provide the most favourable circumstances for the formation and preservation of this com

ISSN:0021-8871    

DOI:10.1002/jctb.5010110702

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010110703

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractAn assessment of inhibition ability was obtained by two test procedures, which yielded the minimum threshold concentration (range) at which an additive prevents the corrosion of ferrous materials in non‐acid aqueous solutions containing dissolved air. An accelerated procedure was also adopted, in which the basis solution contained a mixture of potassium ferricyanide and sodium chloride.The ability to inhibit the corrosion of zinc was assessed by weight loss experiments.Stationary current/potential polarisation curves, as well as current/time and potential/time curves, were obtained with a cell which incorporated an iron test specimen as anode, suitably ‘activated,’ a large well‐aerated inert cathode, and a non‐acid aqueous el

ISSN:0021-8871    

DOI:10.1002/jctb.5010110704

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe methods described in Part I1were applied to the screening of over 400 possible inhibitors, mainly organic, in non‐acid aqueous solutions containing dissolved air, and to supporting polarisation experiments.Inorganic anions tested included sodium azide which inhibits rusting although it forms a soluble complex with ferric ions and does not precipitate ferrous ions. Some heavy metal complexes, such as potassium ferrocyanide and a ferric EDTA complex, were inhibitors.The carboxylate anion favoured inhibition although this tendency is modified by the hydrocarbon residue and substituents. Thus in the series of sodium salts of fatty acids, the inhibitor effectiveness was maximum with a molecule containing 8—10 carbon atoms depending on the type of test.Results for amines indicate that inhibition is due to the neutral amine molecule; only with strong amines could inhibition be due partly or mainly to the hydroxyl ion. This conclusion is supported by the lack of inhibition ability of aliphatic amino‐acids of comparatively low molecular weight, since aqueous solutions of these exist mainly as zwitter ions. Sodium lauroyl sarcosinate, which is an amide‐type derivative of sarcosine with a large hydrocarbon part, has however good inhibiting properties except in presence of halide ions.Most non‐basic nitrogen compounds were ineffective, even including many derivatives of hydrazine which itself is used as an inhibitor and oxygen scavenger in boiler feed water. Maleic hydrazide and its derivatives were however exceptionally effective, although only moderately so in presence of halide. The nitro group favoured inhibition ability with water‐soluble compounds; the nitroso group favoured inhibition unless, as appeared usual, the molecule complexes iron; and the azo group appeared ineffective.Some but not all organic derivatives of phosphoric acid inhibited the rusting of steel, whilst two phosphinic oxides were ineffective.The sulphonate group resembles sulphate in that it opposes an inhibition tendency. Unlike halide ions, covalent halogen assists inhibition when present in themeta‐ orpara‐, but not in theortho‐position to the carboxylate group in benzoate.Polarisation curves showed most inhibitors to polarise anodic dissolution rather than cathodic

ISSN:0021-8871    

DOI:10.1002/jctb.5010110705

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe influence of pH, apart from the case of amines discussed in Part II,1and geometrical factors on the inhibition thresholds for mild steel in non‐acid aqueous solutions containing dissolved air, are described. Modifying the standard corrosion tests by partial or complete removal of the air‐formed oxide film increased the inhibition threshold concentration with some but not all inhibitors. Conversely, pre‐immersing the specimen in an inhibiting solution reduced the threshold value below the normal value.Substances which form soluble iron complexes, such as catechol and EDTA, were often found to increase the inhibition threshold for mild steel, but the results nevertheless indicate that inhibition is not necessarily associated with the deposition of an insoluble iron salt. The iron complex solutions were themselves found to inhibit in some instances, a fact probably relevant to the well‐known inhibition effect of tannins.Generally no marked differences appeared in the threshold values for a number of irons and low alloy steels. Azide showed a resemblance to nitrite in its behaviour, which suggests a similar inhibition process, i.e. adsorption. The cast irons, especially the ferritic varieties, were considerably more difficult to inhibit. Many inhibitors for ferrous materials were also found to inhibit zinc corrosion, which indicates that unfilled electron energy bands or vacant atomic orbitals are not necessary for inhibition to occur.The results described in the three papers of this series are summarised, and a novel hypothesis is presented by one of us (P.H.) to account for inhibition by

ISSN:0021-8871    

DOI:10.1002/jctb.5010110706

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY

摘要:

AbstractThe response to hydrogenation and catalytic cracking of the various types of hydrocarbons present in petroleum gas oils has been investigated by mass spectrometric analytical techniques. A substantial difference was found between the ease of hydrogenation of mononuclear and dinuclear aromatic compounds. A similar difference does not appear to exist between dinuclear and polynuclear aromatic systems. Some polynuclear compounds are apparently hydrogenated completely under conditions which do not normally saturate mono ring aromatics.In catalytic cracking, it appears that aromatic compounds are affected largely by the cracking of aliphatic appendages and very few aromatic rings are broken, whereas entirely aliphatic materials present in the reactant stream are cracked quite readily. It is well known that hydrogenation is beneficial to a catalytic cracking charge stock. This work shows that relatively mild hydrogenation of materials which are to be catalytically cracked can, by saturating polyaromatics only to monoaromatics (naphthenes), make the stock much more susceptible to cracking.

ISSN:0021-8871    

DOI:10.1002/jctb.5010110707

出版商:John Wiley&Sons, Ltd    

年代:1961

数据来源: WILEY