Abstract: The Abstract of the Invention is a method of making a solution of the nitrates of iron and chromium from a spent catalyst containing oxides of iron and chromium, which method comprises:(a) dissolving the catalyst in sulphuric acid;(b) reacting the resulting sulphates solution with a source of nitrate ions and of cations of which the sulphate is of low solubility, whereby to precipitate such sulphate;(c) separating the sulphate, whereby to give a nitrates solution of low sulphate content.

Abstract: Hydrotreating catalysts are prepared using multiple impregnation and a critical ratio of VIB metal to VIII metal in one or more stages to produce catalysts which have higher than normal activity in contaminant removal from hydrocarbon feed stocks, especially in both sulfur and nitrogen removal, which catalysts also contain relatively low or no acidic residues such as P.sub.2 O.sub.5 and permit use of lower effective operating temperature for a predetermined percentage of contaminant removal, for example, at 85% removal of sulfur.

Abstract: The Abstract of the Invention is a method of making a solution of the nitrates of iron and chromium from a spent catalyst containing oxides of iron and chromium, which method comprises:(a) dissolving the catalyst in sulphuric acid;(b) reacting the resulting sulphates solution with a source of nitrate ions and of cations of which the sulphate is of low solubility, whereby to precipitate such sulphate;(c) separating the sulphate, whereby to give a nitrates solution of low sulphate content.

Abstract: A method of preparing a solution of the nitrate of iron and mixed chromium from a spent iron oxide-chrome oxide shift catalyst which comprises dissolving said spend iron oxide-chrome oxide shift catalyst with nitric acid in the presence of from 5-25% by weight of the catalyst of an additive selected from the group consisting of ferrous sulfate and sodium thiosulfate.

Abstract: Porous silica particles useful in catalysis are prepared by adding excess alkali to a body of water glass; the excess alkali is responsible for increasing the pore diameter.

Abstract: The addition of citric acid to large amounts of catalyst fines allows their incorporation into catalyst formulations without the loss of important physical properties.

Abstract: A method for preparing a hydrotreating catalyst having a controlled pore distribution is disclosed. The method requires adding to the alumina prior to forming from 0.1 to 15% by weight of a water soluble polycarboxylic acid having from 2 - 22 carbon atoms. The resulting formed alumina support after being calcined has a pore volume distribution such that most of the pore volume in pores greater than 200 A in diameter as measured by Mercury penetration porosimitry is substantially eliminated. The pore volume as measured by nitrogen adsorption in the range of between 100 A and 1200 A is reduced. The polycarboxylic acid may be added to the catalyst carrier prior to forming in different ways such as by dissolving the catalytically active metals with the water soluble polycarboxylic acid and then impregnating hydrothermally or by pore volume or by adding a water soluble polycarboxylic acid salt to the hydrous or xero gel after precipitation.

Abstract: Porous silica-alumina products useful in catalysis are prepared by adding excess alkali to a body of water glass, the excess alkali is responsible for rendering the product extrudable and for increasing the pore diameter.