Patent GB-925173-A (GB)
Title: Process for the catalytic oxidation of hydrocarbons
Inventor: BENICHOU SAMUEL
IPC: C10G51/00
Filed: 1959-05-22
Abstract: Apparatus for the catalytic vapour phase oxidation of hydrocarbons to organic products (see Group IV(b)) comprises a series of chambers each containing a fixed catalyst bed and linked by conduits comprising cooling means, the volume of catalyst increasing from one chamber to the next in a prescribed manner. One form of apparatus comprises a tube of constant cross-section in which successive spaced lengths are filled with catalyst, cooling means being provided between each filled section.  Another form of apparatus comprises a series of separate chambers, whose volumes may also increase progressively from one to the next.ALSO:A process for the catalytic partial oxidation of a hydrocarbon capable of being partially oxidised in vapour phase to a specific organic oxidation product by means of an oxygen-containing gas, the yield of the specific oxidation product being maximum at a predetermined temperature comprises passing at a constant rate a mixture of the hydrocarbon vapour and the oxygen-containing gas, p  in which the amount of hydrocarbon per unit volume of the mixture is below the explosion threshold, through a series of chambers interconnected by conduits each chamber containing a fixed-bed catalyst the volume of which increases from one chamber to the next in such a manner that the same quantity of hydrocarbon is oxidised in each chamber, the temperature of the mixture in each chamber being raised by the heat liberated by the oxidation of the aforesaid quantity of hydrocarbon from a value below to a value above the predetermined temperature, the said values being the same for each chamber in the series, the temperature of the mixture fed to the first chamber being at the value below the predetermined temperature and the mixture being cooled in its passage between successive chambers to the value below the predetermined temperature.  When the chambers permit adiabatic oxidation, the volumes of catalyst in successive chambers from the first to the penultimate chamber are proportional to the series of values <FORM:0925173/IV(a)/1> n being the number of chambers determined in accordance with the equation <FORM:0925173/IV(a)/2> where H is the temperature rise per unit volume of the said mixture which would be obtaned by oxidation of the total quantity of hydrocarbon therein and D T is the temperature difference between the said values below and above the predetermined temperature.  Substantially complete exhaustion of the hydrocarbon in the flowing mixture is achieved by using a volume of catalyst in the last chamber which is three times the volume of that in the penultimate chamber.  An alternative method is given for calculating the volume relationships.  When the chambers do not permit adiabatic oxidation then, D being the fraction of the heat lost in each chamber, the volume of catalyst in successive chambers is increased from the second to the penultimate chamber according to the series of values <FORM:0925173/IV(a)/3> and the number of chambers is altered to n(1-D).  One form of apparatus comprises a tube of constant cross-section in which successive spaced lengths are filled with catalyst, cooling of the reaction gases being effected between each catalyst bed by, for example, injection of water.  An example describes the oxidation of naphthalene to phthalic anhydride wherein (Fig. 2, not shown) naphthalene flows from storage 1 to a mixer 6 where it is mixed with air supplied by pump 9.  The mixture of naphthalene and air flows via heaters 11 and 12 through a series of catalytic chambers 13a to 13e, containing beds of vanadium oxide or molybdenum oxide whose volumes increase progressively in prescribed manner.  The gases enter each chamber at 350 DEG C. and leave at 410 DEG C. and are then cooled to 350 DEG C. by injection of water by atomisers 14a-14f.  The gases leaving the last reactor 13g are passed via heat exchanger 11 to a series of condensing chambers 17 for recovery of the phthalic anhydride.  The vessels containing the catalyst beds may if desired be of uniform size and the cooling of the reaction gases may be effected by other described means comprising indirect cooling.