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United States Patent N91 [1]] 4,016,105 Kerr [45] ~ Apr United States Patent n91 [1]] 4,016,105 Kerr [45] ~ Apr. 5, 1977 [54] CATALYST PREPARATIVE METiioi)‘ Primary Examiner-Patrick P. Garvin [75] Inventor: Ralph 0. Kerr, Houston, Teri: _ Attorney, Agent, or Firm--N. Eitdn Dry; Kenneth H. Johnson [73] Assignee: Petro-TexHouston, Tex.Chemical [22] Filed: Feb. 7, 1975 [57] ABSTRACT [21] App]. No.: 548,163 - C, vanadium - phosphorus oxidation catalysts for pro ‘[52] new. ............................. .. 252/4311252/435; ducing maleic acid are prepared in an aqueous phos 21591346311 phoric acid solution using a reducing agent comprising [51] Int. (:1.2 ........................................ ..|1501_J27/1s an organic acid or aldehyde and a secondary alcohol such as oxalic acid and ethanol in a mole of 1:1 to 3 [58] Field oiSearch ...... ., ........... .1 ..... ..2$2_/437,435 respectively, in which an inorganic vanadium com [56] References Cited pound such as V205 is dissolved and reduced to vana UNITED STATES PATENTS ‘ dium of 5+ valency or less. 3,156,707 11/1964 Kerr ........................... ..1.25i/437x 3,433,823 3/1969 McMahon .... .. 252/437x 3,864,280 2/1975 Schneider ................... 252/437 x -8 Claims, N0 Drawings 4,016,105 ll 2 compound such as tellurium tetrachloride and an alkali CATALYST PREPARATIVE METHOD such as potassium chloride. After the exothermic reac tion between the ingredients the catalyst may be used. BACKGROUNDJOF THE INVENTION _ The reaction mixture may be formed onto carriers or The present invention relates to an improved method 5 shaped into forms such as pellets prior to the reaction of preparing catalysts for use in the oxidation of hydro to form the catalyst. carbon to prepare dicarboxylic acids and anhydrides. Another example of the preparation of the catalyst More particularly, this is an improved method‘ of pre complex is to dissolve the copper, Me and alk metal paring phosphorus - vanadium catalyst. compounds and a vanadium compound such as ammo The present catalyst preparative method provides a nium metavanadate or vanadium pentoxide in an aque simple, easily performed process, which avoids concen ous solution of phosphoric acid. After the components trated acid solutions, and corrosive re?ux situations. have been dissolved the solution is heated until precipi Basically, all‘of the methods disclosed in the prior art tation occurs. The precipitant can then be dried and seek to obtain the vanadium in a valence state of less used as a catalyst, or a carrierf’may be combined with than .5. the liquid phase either before or after the precipitation. A typical catalysts preparation may involve dissolv It is an advantage of the present invention that con ing the vanadium, phosphorus, and other components centrated solutions of strong acids are not employed. It in a common solvent, such as hot hydrochloric acid and is a further advantage of the present process that rigor thereafter depositing the solution onto a carrier. The ous re?uxing of the components to reduce'the vana reduced vanadium with a valence of less than 5 is ob 20 dium portion thereof is not required. A feature of the tained by initially using a vanadium compound with a present invention is its simplicity of operation. These valence of plus 5 such as V205 and thereafter ‘reducing and other advantages and features of the present inven to the lower valence with, for example, hydrochloric tion will be clearly apparent from the following discus acid during the catalyst preparation to form the vana slon. dium oxysalt, vanadyl chloride, in situ. The vanadium 25 ‘compound is dissolved in a reducing solvent, such as SUMMARY OF THE INVENTION hydrochloric acid, which solvent functions not only to Brie?y stated, the present invention is a method of form a solvent for the reaction, but also to reduce the preparing a phosphorus - vanadium oxidation catalyst valence of the vanadium compound to a valence of less comprising adding an organic acid or aldehyde reduc than 5. For example, a vanadium compound, a, copper ing agent, preferably, having one to 18 carbon atoms, compound, a tellurium compound, phosphorus com and more preferably, one to 81 carbon atoms; such as pound and alk metal compound may be dissolved in for example, oxalic acid, citric acid, formic acid, ascor any order in a suitable reducing solvent and the“ forma bic acid, malic, formaldehyde, acetaldehyde or mix tion of the complex allowed to take place. Preferably, tures thereof and a coreducing agent comprising a the vanadium compound is ?rst dissolved in the solvent secondary alcohol having 3 to 1.2 carbon atoms such as, and thereafter the phosphorus, copper, tellurium and isopropanol, Z-butanol, 2-pentanol, 3-pentanol, 2 other metal compounds, if any, are added. The reaction octanol, 6-dodecanol, and the like, to an aqueous solu to form the complex may be accelerated by the applica tion of phosphoric acid, heating said solution to a tem tion of heat. The deep blue color of the solution shows perature in the range of 50° to 80° C., adding an inor the vanadium has an average valence of less than 5. ganic vanadium compound to this aqueous solution, The complex formed is then, without a precipitation maintaining the temperature of the reaction mixture in step, deposited as a solution onto a carrier and dried. In the range of 50° to 80° C, until all of said vanadium this procedure, the vanadium has an average valence of compound is dissolved and the valence of dissolved less than plus 5, such as about plus 4, at the time it is vanadium is less than 5", andrecovering a vanadium - deposited onto the carrier. Generally, the average va 45 phosphorus composition. lence of the vanadium wil be between about plus 2.5 and 4.6 at the time of deposition onto the_car'rier. DETAILED DESCRIPTION {OF THE INVENTION In another method the catalyst is prepared by precip In carrying out the present invention, it has been itating the metal compounds, either with or without a found desirable to employ the vanadium compound in carrier, from a colloidal dispersion of the ingredients in an incremental amount. The incremental amount of an inert liquid. In some instances the catalyst may be vanadium compound is added to the water solution of deposited as molten metal compounds onto a carrier; phosphoric acid and reducing agent as described however, care must be taken not to vaporize off any of above, wherein also only a portion of the total reducing the ingredients such as phosphorus. The catalysts have agent is initially present. In order to maintain vanadium also been prepared by heating and mixing anhydrous in a valency of less than plus 5, ‘the solution must have forms of phosphorus acids with vanadium compounds, a blue color. Hence, as vanadiumcompound is added copper compounds, Me compounds, and the alk - incrementally, also, the reducing agent (which is a metal compound. The catalysts may be used as either combination of an acid or aldehyde and a secondary ?uid bed or ?xed bed catalysts. In any of the methods alcohol) is added incrementally to maintain the blue of preparation, heat may be applied to accelerate the 60 color. Generally, the reducing composition will be used formation of the complex. in excess of the stoichiometric amount necessary to Another example of the catalyst preparation is to mix reduce the vanadium below the plus 5 valency. Of the with heating at a temperature of about 100° to 600° C. reducing composition, it is generally preferable that the an anhydrous phosphoric acid such as ortho-phos secondary alcohol be present in excess, since it is easily phoric acid, pyrophosphoric acid, triphosphoric acid or 65 recovered and recycled. metaphosphoric acid with a vanadium compound such The alcohol portion of the reducing composition is as vanadium pentoxide or ammonium metavanadate, a present in the range of about 1 to 3 moles of alcohol copper compound such as copper (II) chloride, a Me per mole of acid or aldehyde. Preferably, the alcohol is 4,016,105 3 4 present in excess, thus, in the event that there is unre nents of the catalyst. The x in face has no determinate acted reducing agent, the equilibrium of the system will value and can vary widely depending on the combina favor the excess being the secondary alcohol, which as tions within the complex. That there is oxygen present noted above is easily recovered and recycled. is known and the O, is representative of this. A more The amount of water present in the present aqueous speci?c group of Me components is Te, Zr, Ni, Ce, W, system is about 3 to 20 times by weight of the vanadium Pd, Ag, Mn, Cr, Mo, Re, Hf, Ta, Th, Co, U, Sn or composition to be dissolved therein. More preferably, mixtures thereof. about 8 to 12 times the weight of the vanadium com A more perferable catalyst is one wherein Me is Te, pound. Ni, Ce, Cr, Mo, Re, Hf, Ta, U, or mixtures thereof. The phosphorus is derived from a speci?c source, ‘One preferred embodiment of the catalyst complex i.e., phosphoric acid, which is present in order to pro comprises vanadium - phosphorus, copper, a second vide an atomic ratio of vanadium to phosphorus in the metal, Me, and an alkali or alkaline earth metal, (Alk range 1:1. 1 2 to 1.16. The phosphoric acid may be such metal) of group IA or [IA of the Periodic Table of as, orthophosphoric acid, pyrophosphoric acid, tri Elements. This complex may be represented by the phosphoric acid or metaphosphoric acid. 15 con?guration After all of the reactants have been added to the reaction system, it is re?uxed for a period of time; for V P,I CubMetALlQO, example, a few minutes to several hours in order to solubilize all of the components, particularly the vana wherein Me, a, b, c, and x are as described above and dium compound which may be insoluble under normal 20 Alk is a metal selected from the group of elements of conditions.
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