in one aspect the invention is directed to improved catalyst compositions comprising titania to which phosphorous derived from polyphosphoric acid has been chemically bonded by thermal activation . in another aspect of the invention , such catalysts are used in producing essentially linear polyethylenepolyamines such as diethylenetriamine , triethylenetetramine , tetraethylenepentamine and pentaethylenehexamine from the reaction of ethylenediamine and monoethanolamine . the inventor is unaware of the precise structural differences between the claimed catalysts and previous phosphate catalysts which have been tried in such reactions , but is cognizant of substantially higher rates of conversion to linear polyethylenepolyamines with the claimed catalysts . the novel phosphate compounds catalyze the reaction of ethylenediamine and monoethanolamine at a temperature of from about 250 ° c . to about 400 ° c ., preferably from about 300 ° c . to about 350 ° c . and a pressure of from about 500 to about 3000 psig . and preferably from about 1000 to about 2000 psig . higher temperatures or pressures can be used , but there is no particular advantage in using such higher temperatures and / or pressures . the ratio of ethylenediamine to monoethanolamine may range from about 1 : 2 to about 5 : 1 . the pelleted catalyst compositions of the present invention are normally employed as a fixed bed of catalyst in a continuous reaction system . in a continuous process of this nature , the time of contact of the reactants with the catalyst is one of the interrelated factors that those skilled in the art will adjust , along with temperature , pressure , bed geometry , pellet size , etc . in order to obtain a desired rate of reaction and , hence , a desired percentage of conversion of the reactants . thus , in a continuous process , it is not necessary to drive the reaction to completion because unreacted feedstock components can be recycled to the reactor . it is customary to use cylindrically - shaped catalyst pellets having a diameter essentially equal to the length thereof , such as diameters and lengths ranging from about 1 / 32 &# 34 ; to about 3 / 8 &# 34 ;. it will be understood that the shape and dimensions of the pellets are not critical to the present invention and that pellets of any suitable shape and dimensions may be used as desired , by one wishing to practice the process of the present invention . when cylindrical pellets of catalyst of the type described above are used , the weighted hourly space velocity may be varied within wide limits ( e . g ., 0 . 1 to 5 w / hr / w ) in order to obtain a desired rate of conversion , as explained above . normally , space velocities of about 0 . 5 to 2 w / hr / w will be employed . catalyst life is an important factor in conducting a continuous reaction . for example , if a catalyst is easily poisoned , or if catalyst pellets do not have good structural properties , the economics of the process will be seriously and adversely affected . the catalysts of the present invention are not particularly susceptible to poisoning so this normally does not present a problem . however , under the reaction conditions employed , amines of the type used and formed herein have the potential capability of leaching or otherwise adversely affecting the structural integrity of the pellets . in an extreme instance , catalyst pellets having good initial crush strength and surface hardness will be reduced to fines very rapidly when used under reaction conditions such as those employed herein . it is a feature of the present invention that the pelleted catalyst compositions have improved resistance to physical degradation when used to catalyse the reaction of monoethanolamine with ethylenediamine . the catalyst composition of the present invention is prepared by treating titania with polyphosphoric acid to provide a phosphorous - containing titania supported catalyst composition . titania pellets may be prepared by extrusion or by compaction in conventional pelleting apparatus using a pelleting aid such as graphite . it is also within the scope of the present invention to deposit the polyphosphoric acid on powdered titania followed by pelleting and , if desired , calcination . polyphosphoric acid is used as the source of the phosphorous . in general , the pelleted composition should contain at least about 0 . 5 weight percent of phosphorus . when the catalyst composition is to be prepared by impregnating a preformed pellet , a suitable procedure to be used is to heat polyphosphoric acid at a temperature of about 100 ° to about 150 ° c . and to then add pellets in an amount about equal to the volume of the heated liquid . this treatment should be continued from about 0 . 5 to about 5 hours . at the end of that time , the resulting mixture of pellets and liquid may be cooled , decanted to remove excess liquid followed by washing with an amount of water adequate to substantially completely remove un - adsorbed liquid . temperatures above 150 ° c . can be used , if desired , but there is no particular advantage in doing so . it will be understood that the phosphorous that is present on a thus - treated pellet is not present as elemental phosphorous , but rather as phosphorous that is chemically bound , probably as an oxide , to the support . this is demonstrated by the fact that repeated washing will not remove all of the phosphorous . however , the exact nature of the bonding is not completely understood . the amount of phosphorous that is bonded or otherwise adheres to the support is a function of heating and other conditions used in the treating step and is also a function of the chemical identity of the phosphorous compound that is used as a source of phosphorous . under the treating conditions exemplified above , at least about 2 . 5 wt % of phosphorous is caused to bond or otherwise permanently adhere to the pellets . there is an upper limit to the amount of phosphorous that bonds or otherwise permanently adheres to the support . this upper limit is , as indicated , a function of both the treating conditions and the chemical used as a source of the phosphorous . normally , the maximum amount of phosphorous that can be caused to bond or otherwise permanently adhere to the pellets is within the range of about 5 to 10 wt %. when the pellets are impregnated with the phosphorous compound at a temperature of at least about 100 ° c ., there is no absolute need to calcine the catalyst composition before use . however , the pellets can be calcined , if desired , as a precautionary measure and / or in order to still further improve the physical properties of the pellets . the pellets are suitably calcined at a temperature of about 200 ° c . to about 800 ° c . for a period of time within the range of 2 to 24 hours ; more preferably at a temperature of about 500 ° c . to about 700 ° c . for abut 4 to 16 hours . other procedures can be used in adding phosphorous to the support . for example , the pellets can be treated with polyphosphoric acid at ambient temperatures or at more modest elevated temperatures of less than about 100 ° c . in this situation , however , it is necessary to thermally activate the treated pellets by calcining under the conditions recited above . alternatively , the support can be treated with the polyphosphoric acid in powdered form and the powder can thereafter be pelleted . if the treatment is conducted at a temperature of about 100 ° c . or more , thermal activation will normally have been obtained and it will not be absolutely necessary to perform a calcining operation . if lower treating temperatures are used , calcining is a desired operation . the calcining operation can be conducted prior to or subsequent to the pelleting step . any appropriate pelleting procedure of the type known to those skilled in the art may be used . for example , the treated powdered support can be mixed with graphite and / or other binders and compacted or extruded under conventional conditions . there are many compounds which can be formed from the reaction of ethylenediamine and monoethanolamine besides the preferred linear polyethylenepolyamines such as diethylenetriamine , triethylenetetramine , tetraethylenepentamine and pentaethylenehexamine . less desirable cyclics and other compounds , such as piperazine , n -( 2 - aminoethyl ) ethanolamine and n -( 2 - aminoethyl ) piperazine , are also formed . the more desired linear polyethylenepolyamines can be easily recovered from the reaction product mixture by conventional methods such as distillation . such distillation recovery methods are well known in the art . an outstanding advantage of the claimed invention is that the lower molecular weight polyethylenepolyamines recovered from the reaction mixture can be further reacted with monoethanolamine to produce a larger perecentage of the higher molecular weight linear polyethylenepolyamines . the following examples will further illustrate the preparation of predominantly linear polyethylenepolyamines from ethylenediamine and monoethanolamine by the use of the catalyst compositions of the present invention . they are given by way of illustration and not as limitations on the scope of the invention . thus , it will be understood that reactants , proportions of reactants , and time , temperature and pressure of the reaction steps may be varied with much the same results achieved . for purposes of convenience and brevity , the reactant compounds employed and the products obtained have been abbreviated in the following examples and tables . the abbreviations employed for these various compounds are : pelleted catalysts were prepared by depositing phosphorus on a titania support . a titania support containing phosphorous was prepared by heating about 1 kg of polyphosphoric acid to about 130 ° c . under an inert atmosphere in a flask fitted with a condenser . about 110 cc of titania pellets were slowly added through the condenser and the temperature was maintained for two hours . thereafter the catalyst was recovered by first decanting the excess polyphosphoric acid followed by the addition to the pellets of a large quantity of water . the pellets and water were slowly stirred to dissipate heat . the pellets were washed several times with copious amounts of water and dried . for convenience , the catalyst prepared and a brief description of the same is set forth herein as table i . table i______________________________________titania catalyst compositionsnumber composition______________________________________5464 - 72 40 wt . % phosphate on alumina5494 - 4 titania ( tio . sub . 2 ) 5494 - 18 titania treated with polyphosphoric acid ( ppa ) for 2 hours5494 - 87 titania treated with polyphosphoric acid for 2 hours and then calcined for 16 hours at 600 ° c . ______________________________________ preparation of polyethylenepolyamines from ethylenediamine and monoethanolamine using titania containing phosphorus derived from polyphosphoric acid the catalysts described in table i were utilized for the conversion of ethylenediamine and monoethanolamine to a polyethylenepolyamine reaction product in a 100 cc continuous reactor system . pellets were placed in the reactor and the feedstock that was fed to the reactor with a mixture of ethylenediamine and monoethanolamine in a molar ratio of about two moles of ethylenediamine per mole of monoethanolamine . in order to obtain a basis for comparison , the reaction temperature was varied so as to obtain about a 65 % conversion of the monoethanolamine feedstock . the reaction product was periodically sampled and analyzed by gas chromatographic analysis of the crude reactor effluent . results were calculated on a feed - free basis . the catalysts tested and the results obtained in the series of tests are set forth in table ii . in general , each feedstock was run for at least 21 / 2 hours to make sure that reaction conditions had stabilized . referring now to table ii it will be seen that the reference catalyst composition ( 5464 - 72 ) which comprised a commercially available 40 wt . % phosphate on aluminia catalyst of the type disclosed in brennan u . s . pat . no . 4 , 103 , 087 at column 8 , lines 50 - 54 , gave less satisfactory results than those obtained with the catalyst of the present invention . this run shows that with a pelleted aluminum phosphate catalyst , and in a continuous reaction , the results obtained are not so favorable as those reported for batch reactions in the copending application ser . no . 283 , 713 . in particular , note that only about 77 % of the triethylenetetramine fraction was noncyclic with this run . in contrast , with the catalyst of the present invention the noncyclic content was normally in excess of 90 %. note also that there was also a significantly smaller yield of diethylenetriamine with the reference catalyst . the second reference tests ( 5494 - 4 ) was untreated titania pellets and it is seen that they were essentially inert insofar as conversion of monoethanolamine and ethylenediamine is concerned . thus , table ii demonstrates that with titania supported pelleted catalyst in a continuous reaction system , it is possible to obtain excellent results in the reaction of monoethanolamine with ethylenediamine . the percentage of noncyclic reaction products is very high , being over 90 %. diethylenetriamine yields of from about 60 to about 75 % were obtained with this catalyst . uniformly good yields of triethylenetetramine were also obtained . table ii__________________________________________________________________________titania supported phosphorous catalystsphosphorous temp ., 0 ° c . selectivity ratio : on cat . @ 65 % aep & amp ; deta teta pelletcatalyst ( wt . %) mea conv . pip . deta aeea hep teta tepa pip % n . c . strength__________________________________________________________________________5464 - 72 333 6 . 7 38 . 5 2 . 6 4 . 5 18 . 3 5 . 9 7 . 7 775494 - 4 -- -- -- -- -- -- -- -- -- 5494 - 182 . 4 309 2 . 5 64 . 0 0 . 5 1 . 8 16 . 8 ˜ 3 25 . 5 96 11 . 65494 - 872 . 3 334 ˜ 3 ˜ 73 0 . 8 ˜ 3 ˜ 20 ˜ 98 5 . 0__________________________________________________________________________ there are times when it is desirable to obtain greater yields of the higher polyethylenepolyamines such as triethylenetetramine or tetraethylenepentamine than those reported herein . in such instances , the diethylenetriamine can be recycled by substituting diethylenetriamine for all or a part of the ethylenediamine feedstock . this specification not only includes data related to the invention disclosed and claimed herein but also , for comparative purposes , discloses data that is also disclosed and claimed in vanderpool u . s . patent application ser . no . 455 , 160 , filed jan . 3 , 1983 of an even date herewith , and entitled : &# 34 ; catalysts and preparation of linear polyethylenepolyamines therewith &# 34 ; the foregoing examples of the present invention have been given by way of illustration only and are not intended as limitations on the scope of the invention which is defined by the following claims .