Montmorillonite Cracking Catalyst U
J
DEMONSTRATION OF PRESENCE OF HYDROGEN ION IN HEATED FILTROL CLAY CATALYSTS ALEXANDER GRENALL Union Oil Company of California, Wilmington,Cali,f.
The presence of hydrogen ion in Filtrol clay catalyst over the entire range of catalytically important cracking temperatures was established by a physicochemical titration method. The method is described and data presented to show that the hydrogen ion content is a linear function of the temperature at which the catalyst is heated in air. It is possible to calculate the decomposition temperature of montmorillonite clay from this relationship. The mean value of this decomposition temperature, calculated for several different batches of catalyst, agrees with that found experimentally by x-ray and differential thermal analysis. The effect of steam treatment on the hydrogen ion content of Filtrol catalyst is nonlinear. Isothermally, with increasing steam concentration, an apparent equilibrium point dependent upon the isotherm temperature is reached for hydrogen ion removal. A t constant steam concentration, increasing the temperature at which this catalyst is heated results in lowered hydrogen ion contents. The factor of time of heating was examined in a preliminary fashion. Hydrogen ion content of this clay catalyst is correlated with x-ray diffraction data.
I
N T H E previous paper of this series, x-ray diffraction results (8) were presented leading t o the postulation of the presence of hydrogen ion and/or water in the structure of montmorillonite clay after calcination of the Filtrol catalyst at temperatures of 1050' t o 1475' F. This paper develops experimental evidence for the presence of hydrogen ion in a clay cracking catalyst of this type and demonstrates a correlation with x-ray diffraction data. The possible continued existence of base-exchangeable adsorbed hydrogen ion on montmorillonite over the entire range of catalytically important temperatures was investigated by means of a titration method wherein a known weight of catalyst was titrated with alkali in the presence of a strong salt solution, the course of neutralization being followed by a glass electrode-calomel cell. EXPERIMENTAL METHODS
As for the x-ray diffraction studies, the Filtrol clay catalyst
used was the commercial grade pellet (Filtrol Corporation, Los Angeles, Calif.). Several batches prepared at different, times were examined t o obtain representative results. Samples of these batches were heated a t temperature for definite periods of time in the respective atmospheres of air and steam and then analyzed for hydrogen ion content in the manner described below. A charge of finely ground catalyst was weighed out on a n analytical balance, transferred t o the titration vessel, and 100 mi. of a 5y0 sodium chloride solution were added so as to wash t h e sample down and disperse it. Using a n electronic titrometer (Shell Development dual titrometer, Precision Scientific Comany, Chicago, Ill.) calibrated for p H settings against a standard guffer solution, the initial patof the catalyst was determined and, thereafter, 2.00-ml. additions of a 0.01 M potassium hydroxide solution, standardized against potassium acid phthalate by means of the titrometer, were made with a time interval of 1.25 minutes allowed t o elapse after each addition before reading the pH. The d a t a from these titrations were plotted and from the curves obtained the titer of each sample was evaluated.
EXPERIMENTAL CONDITIONS USED IN TITRATION METHOD
I n the author's preliminary studies, a solution of 5% sodium chloride in water was arbitrarily chosen as the titration medium on the assumption t h a t the presence of a fairly high salt concentration would facilitate the exchange of a sodium ion for a hydrogen ion held on the base exchange centers of montmorillonite and permit the ready determination of the latter by titration with alkali. T o establish the optimum concentration of salt,
.I20 0
5
IO
15
NaCl CONCENTRATION
20 I W t %)
Figure 1. Effect of Sodium Chloride Concentration on Filtrol Titration
titrations of Filtrol catalyst, batch H-292, were performed in 0, 2.5, 5, 10, and 20% sodium chloride solutions. Table I and Figure 1 present the results. These indicate a maximum in titer values lying between 2.5 and 5% salt concentrations. S o explanation for this effect can be offered a t this time. Because 5% salt solution as a medium is well up on the peak it was decided t o continue its use.
TABLEI. DETERMINATION O F OPTIMUM S O D I E M CHLORIDE CONCENTRATION FOR TITRATION MEDIGN (Union Qil Co. sample 160, batch H-292)" HA, L I o l e i K p NaCl 0 0 123
%j
10
5
0 165 0.164 0 14:
20
0 147
21/2
Conditions. temperature. 112.?1~H.; time elapsed, 6 hours samples, 2 grams. a
iveizht of
The influence of catalyst weight'per volume of medium on the final titer values was investigated. The results given in Table I1 indicate t h a t the proportion of solid sample to volume of liquid medium is not important. The effect of elapsed time between addition of alkali t o the titration mixture and reading of the p H meter was studied. I n one procedure, 1.25 minutes read on a stop watch were allorved between addition and reading. in the other, sufficient time was allowed, often as long as 10 d n u t e s , for the pH to reach equilibrium. Constancy was assumed when the p H reading did not change by more than 1 0 . 0 3 unit per minute. The experimental titer values obtained for three batches of catalyst samples by both methods are given in Table 111. These show t h a t the results obtained'by using carefully timed intervals are sufficiently close t o the equilibrium values so t h a t the shorter method may be used.
1485
INDUSTRIAL AND ENGINEERING CHEMISTRY
1486
TABLE11. INFLUENCE OF S A n i m E WEIGHT TO VOLUMEOF MEDIUMON TITBR (Union Oil Co. sample 160, batch H-292)a Sample Medium Concentration H i Weight, G. Volume, M1. Mole/Kg. 50 0,164 0.5 0,164 50 0.5 0.155 50 0.5 0,147 50 0.5 > I w n = 0 159 1 0 . 0 0 6 1 75 0 163 1 0 153 75 U e a n = 0.158 * 0.005
a Conditions: 590 NaC1.
0.164 0.184 0.164 0.153 0.174 Mean = 0.164 t 0 . 0 0 4 temperature, 1125" P.: time elapsed, 8 hours: medium,
TABLE111. EFFECTO F ELAPSEDTIME
BETWEEN
OF FILTROL CATALYSTS TABLE IV. TITRATION
Union Oil
co.
100 100 100 100 IO0
Samplr 132
Batch H-204
Treatment 500' F., 6 hr. in air
135
H-204
1200' F., 6 hr. in air
145
H-204
1300" F., 6 hr. in air
24
H-208
1100' F., 6 hr. in air
25
H-208
1400' F., 6 hr. in air
1.i9
H-208
1435' F., 6 hr. i n air
The evaluation of hydrogen ion content from the titration data was performed by the usual method of determining the neutralization point from a tangent drawn to t h e inflection in the curve obtained by plotting p H as a function of milliliters of alkali added t o the clay catalyst. Table I17 lists the batch numbers of t h e Filtrol clay catalyst examined, and gives a n abbreviated desciiption of the treatment of each sample, and the concentration of hydrogen ion expressed in moles per kilogram of catalyst. I n Table V are given the calculated values of the inpan of the titers obtained for each sample listed in Table Is' with their precision measures. These data shon that deviations ranging up t o 14% may be expected for any one determination, n i t h a mean percentage average deviation of =t5yo. PRESESCE OF HYDROGEN IONESTABLISHB~D. From these titration data, it is established conclusively t h a t hpdrogrri ion existsinFiltrolcatalystfromroom temperature up toabout 1560°F. and t h a t t h e content of this ion is lonered by inciea-ed temperature of calcination in a n air or steam medium. Soncalrined catalyst has a high concentration of hydrogen ion, 56.2 milliequivalents per 100 grams while practically completely heatdeactivated catalyst has a very low concentration, 0.1 niilliequivalent per 100 grams. The recently proposed cracking mechanisms (a160 isomerization, alkylation, polymerization) of Turkevich and Smith (6) and Hansford (4)require the presence of hydrogen ion. The availability of this ion for such mechanisms is established by the results for Filtrol clay catalyst reported here, mhexe the presence of adsorbed hydrogen ion is demonstrated over the catalytically active temperature range of montmorillonite.
2
1 1
2
1 2 1
H-204
900" F., 6 hr. in 12% steam
77
13-208
1100' F., 6 hr. in 12% steam
79
H-208
1400' F . . 6 hr. in l2V0 steam
134
H-208
2 1 1 1 2 1 2 1 2 1
900' F., 6 hr. in 10070 steam
78
H-208
llOOo F., 6 hr. in 1 0 0 ~ steam o
80
H-208
1400' F., 6 hr. in 100% steam
127
H-241
Unheated
60
H-264
Unheated
128
H-241
850' F., 50 hr. in 100% steam
129
H-241
850' F., 100 hr. in 1007, steam
130
I$-241
850' F.,150 hr. in 100% steam
131
H-241
850' F., 250 hr. in 100'33 eteam
165 136
H-264 H-264
1050' F., 5 hr. in air 1200' F., 6 hr. in air
ALK.4LI
RESULTS OF TITRATION ICXPERIMENTS
Weight Sample Titrated Grams 2 1
133
ADDITIONAND READINGp H o s TITER
Sample Weight, Titer, G. Time Method Mole/Kg. Union Oil Co. Sample 160; Batch H-292; Telnperature, 1 1 2 5 O F.; Time Elapsed, 6 H r . ; 5% NaCl Medium 0.5 Equilibrium 0,164 0.5 1 . 2 5 minutes 0.169 * 0.006 1 Equilibrium 0.163 1 1 . 2 5 minutes 0.158 5 0 . 0 0 5 2 Equilibrium 0.164 2 1.26 minntes 0.164 =t0.004 Union Ojl Co. Sample 135; Batch H-204; Temperature, 1200° F.; Time Elapsed, 6 Hr.: ,570 NaCl Riedinm 1 Equilibrium 0.118 1 1 . 2 5 minutes 0.059 * 0 . 0 0 3 Union Oil C o . Sample 145; Batch H-204; Temperature, 1300° F.; Time Elapsed, 6 Hr.; 5% NaCl Medium 1 Equilibrium 0,064 1 1 . 2 5 minutes 0.061
Vol. 41, No. 7
146
H-264
1300' F.. 6 hr. in air
61 59 26
15-264 H-264 11-264
i400' F., 6 hr. in air 1475' F., 6 hr. in air 1560' IC., 6 hr. in air
2 1 2 1
2 1 0.5 0.5 0 5
0,565
2
1 1
1
1
2
1
0.5 2 1 1
1050' F., 5 hr. in air
H-292 H-292
1050' F., 6 hr. in air 1125' F., 6 hr. in air
144
H-292
1200° F., 6 hr. in air
147
H-292
1300' F., 6 hr. in air
164
H-292
1126O F,,136 hr. in air
153
H-292
1225' F.. 132 hr. i n air
0.142
0.134 0.116 0.115 0.046 0.054 0.132 0.127 0.098 0.110 0.030 0.029 0.576 0.537 0.570 0.118 0,130 0.122 0.128 0.133 0.122 0.125
2 1 1
?I-292
0.061 0.137 0,122 0.066 0.068 0.041 0.041
0.5
1
166 160
0.101 0,096 0.080
2 1 2 1 2 1
2
151
Mole H '/Kg 0.183 0.148 0.112
2
1 0.5 2 I 2 1 2
1 1 2 1
0.122 0.204 0.091
0.074 0.067
0,055 0.066 0,078 0.061
0.003 0.000 0.000
0,214 0.213 0.207 0.164 0.158 0.159 0,127 0.108 0.081 0.060 0.106 0.079 0.102 0.041 0.031
H-204 o H-208
0
H-264
0
H-292
0
3
2 3
0.0400.020-
0.000
900
I
1
1000
1100
I 1200
I 1300
1 1400
1 1500 -1600
TEMPERATURE ( O F )
Figure 2. Effect of Air Hcating on Hydrogen Ion Content of Filtrol Clay Catalyst
INDUSTRIAL AND ENGINEERING CHEMISTRY
July 1949
TABLEV. CALCULATED VALUESOF MEANSAND DEVIATION MEASURESOF HYDROGEN ION DETERMINATIONS GIVEN IN TABLE IV Union Oil Co. Sample 132 135 I45 24 25 169 133 77
Average Deviation 0.018 0.006 0.010 0,008 0,001
Mean en+/&. 0.166 0.107 0.071 0,130 0.067 0,041 0.138
0.000
0,004 0,000 0 . 0045
0.115-
0.050" 0.130 0.104 0,029, 0.557
79
134 78 80
127 60 128 129 130 131 165 136 146 61 59 26
0.002-
0,006" 0.000.~
0.020 0.003 0.006 0.003 0.005 0.001,
0.588
0.124 0.125 0.118 0 . 123.5 0,204 0.083 0,063 0.078 0.061 0.06i 0.001 0.213,
154 153
a
b
Average Deviation 11
GH+
=
ci+ + ACH'
(4)
By rearranging Equation 4, the decomposition temperature, montmorillonite at which the concentration of hydrogen ion is zero is given by tn, of
6 14 6 1 0 3 0.5 8 2
(5)
From the plots for the separatr batches and the use of Equation 1, the constants of the heating curve of each catalyst were calculated and are given in Table VI. Subsequently, through the use of Equation 5, the decomposition temperature for each catalyst batch was obtained. The values for these temperatures are given in Table VI. The mean value of constant a, the hydrogen ion content of catalyst a t 0" F., 0.54 mole per kg., is in fairly good agreement with the value 0.56 mole per kg., for noncalcined catalyst determined experimentdly (Tables IV and V). The average of the decomposition temperatures, 1561' * 70" F., calculated from this relationship, checks the temperature found by x-ray analysis, 1560 "F.( 2 ) ,and thermal analysis, 1562 O F . ( 3 ) . These calculated decomposition temperatures vary from batch to batch of Filtrol catalyst. Whether this variation is real or merely due to experimental uncertainty in the titration results cannot be definitely stated a t this time. Further work is planned to elucidate this point.
6
2 4
0.6 5
2 5 1 10 8
0.0007 0.0007 0.0~05
676 0.2 1
0 011
0 096 0 046
Numerically, however, the slope will be negatively valued. It is possible to rewrite Equation 1 as
%
a a 0,009 0.0:5
0,002
1487
11 0 005 10 Mean of 26 determinations = 1 5 . 4 7 " average deviation. Only one determination was made on this sample. This value was omitted in calculation of mean % average deviation.
EFFECTOF ADDEDSTEAM. Figure 3 gives the plots of the data for several series of samples, from Table V, treated isothermally in atmospheres of 0, 12, and 100% steam concentrations and temperatures of 900 Oq 1100 '. and 1400a F.
TABLE VI. EVALUATION OF CONSTANTS IN EQUATION RELATING H CONTENTAND CALCINATION TEMPERATURE +
Filtrol Catalyst Batch H-204 H-208 H-264 H-292 Mean
b (ACH+/A~) - 2 . 3 3 x 10-4 - 2 . 6 0 x 10-4 - 3 . 5 1 x 10-4 - 5 . 6 0 x 10-4 - 3 , S 1 i 1 O4
a
( C H + at t = 0) 0.381 0.423 0.548 0.790 0 537 * O 135
Decomposition Temperature, F., (n/b) 1635 1627 1561 1420 1561 * 70
RELATIONSHIP BETWEEK HYDROGEN IONCONTEXT AND TEMThe hydrogen ion concentrations were plotted as a function of the heating temperatures in air for batches H-204, H-208, H-264, and H-292. The graphs obtained showed essentially that a dtraight-line reIationship exists between hydrogen ion concentrations and the temperatures a t which samples have been heated. These graphs are not given here in order to conserve space hut instead the titration data for the different catalyst batches have been combined in Figure 2 to show the linearity of the relationship between hydrogen ion conoentration and calcination temperature. The solid line drawn on this graph is that given by the mean of the data for the individual hatches (Table VI) calculated from the empirical equation described later in the paper.
-140 -,/
130.
-I
17
PERATURE.
An empirical equation to fit these curves was derived from
CH' = u
f
I
1 1
1400°F.
?. 0
I
I
I
I
I
20
40
60
80
100
% STEAM
Figure 3. Effect of Steam Treatment a t Various Temperatures Average of all determinations
+ bt
(1) the equation for a straight line, where CH+is the concentration of hydrogen ion in moles per kilogram at t, the calcination temperature in 'F., and a and b are constants. When the calcination temperature is zero then
Ca+ = a
-t
=
C&+
( 2)
The slope of the line, 6, may be expressed as
b = - AC,+ At
(3)
These curves show that the relationship is not linear between hydrogen ion concentration and percentage steam in the atmosphere wherein the catalyst is heated a t a constant temperature. Initially, with low steam concentrations, a large reduction in hydrogen ion is produced. This reduction falls off rapidly as the steam concentration is increased and a steady state is established as shown by the leveling of the curve. With increase in the temperature of the isotherm at which the effect of varying steam concentration is determined, one finds that this steady state
I N D U S T R I A L A N D E N G I N E E R I N G CI-IEMISTRY
1488
point is shifted tovards higher steam concentrations. Thus a t 900" F., apparent equilibrium is reached a t about 28% steam; a t 1100O F. leveling takes place at 38% steam; while at 1400 O F. the point lies a t 70% steam. It may also be seen from Figure 3 that, just as in the case of straight air heating, the higher the temperature a t which a sample is heated in steam, the lover is the concentration of hydrogen ion. This point is amplified by replotting the data, Figure 4, to show the hydrogen ion content as a function of temperature at constant steam concentration. I n contrast t o the curves obtained for air heating, the relationship between hydrogen ion and temperature in a steam medium does not appear t o be linear over the entire range.
%
1
results show that, under these conditions, equilibrium in regard to hydrogen ion content had been established and was maintained throughout the time interval. POSSIBLE 4IECH-INIS3%SOF HYDROGEN POR. RE3rOVAL
The evidence above shows that, under isothermal conditions, increasing t'he steam concent,mtion in t,he atmosphere wherein Filtrol catalyst is heat,ed, results in a n increased removal of hydrogen ion down to a certain limiting value dependent upon the temperature. T h e concentration of steam required t.o reach this steady state point is also some function of temperature. I t is speculated t'hat this steady state is the result of the balance between saturation of hydrogen ion with water molecules to form the hydronium ion and conconiitant desorption of water due to thermal effects so that, a t higher temperatures, higher stonin concentrations are necessary to establish such abalancc (Figure 3 ) . A possible mechanism, t o explain the effect of steam in increasing hydrogen ion removal over t h a t obtained by air heating, is offered here based upon this hypothesis although the author recognizes the oversimplification of reaction kinetics introduced thcrcby. Assuming for the present t h a t hydrogen ion adsorbed on the base exchange centers of montmorillonite clay is essentially nonhydrated after high temperature calcination, one may write that, in the presence of steam,
H + (adsorbed)
+ H20 (vapor pliase)c-I&O+
1 900
I
1000
I 1100
I
1200
I
1300
I
+ 2Hz0
(moiitmorilioiiite (vapor phase) (7)
;Thile in a steam concent,ration sufficient'lv high to saturate all of the hydrogen ion a t a particular temperature,
1400
1500
TEMPER ATUSE,"F.
Figure 4. Temperatnre Effect a t Steam Concentrations
(13)
+ H30+ (adsorbed) + O-structure)
020
(adsorbed)
and that, under the condition of limited s k a m content where complete hydrogen ion saturation with water has not taken place, the folloving reaction is possible
H f (adsorbed) ,040L030
Val. 41, No. 7
Various
l \ e r a g e of all determinations
It may be shovi-n by ext,rapolation of the curves in Figure 4, assuming linearity a t the higher temperatures, that the decomposition temperature of Filtrol catalyst is seemingly lowered by the presence of steam. At 0% steam the curve extrapolates t o a decomposition temperature of about 1650" F.;12% steam yields 1565" F.; vliile 100% steam leads to a temperature of 1505' F. hdmit'tedly, the exact values of these temperatures are in doubt because of the variability in the experimental titer values but the qualitative direction is not t,o be denied. From the study of Filtrol catalyst heated in air arid steam it appears t'hat the mechanisms of hydrogen ion removal in these cases are different. THETIMEFACTOR. The influence of length of time that a sample is held at, a constant temperature TTW examined in a preliminary fashion. The data, from Tables IV and V,for two sets of samples of Filtrol catalyst batch H-292-one heated a t 1125' F. for 6 hours and 136 hours, the other set consisting of a sample heated at 1200" F. for 6 hours and a sample heated at 1225O 5'. for 132 hours-show a significant decrease in kiydrogen ion content n-ith prolonged time of isothermal calcination. The important point t o be derived from these experiments is that a 6-hour air heating does not achieve true equilibrium with regard to hydrogen ion removal. Probably the decrease in hydrogen content, is rapid a t first with t'ime and scttles down to a n equilibrium value for each temperature. Figure 5 s h o w the effect of a long time heating at 850" F. on a Filtrol catalyst, bnt,ch H-241, in t'he presence of 100% steam. Samples a t 50, 100, 150, and 250 hours were examined. T h e
2H30- (adsorbed) -I0 - - (structure) + 3 H 2 0 (vapor phase) (8)
-
I t is assumed furthcr that thc reaction resulting in hydrogen ion removal by air heating may be expressed as 2FI+(adsorbed)
+ O--(structure)
I L O (vapor phase) ( 9 )
A similar set of equations may bc nritten for the removal of hydrogen ion by reaction with hydroxyl groups present in the montmorillonite structure. The possibility should also bc borne in mind that both oxygen and hydroxyl mav be involved sirnultaneously hut whether one or both react does not alter thc fundamental nature of the argumciit t o be advanced.
,100
L--!
I
~
50
100
150
209
___
TbC
TIME IN HOURS
Figure 5. EEect ~f Heating on Filtrd 13-21.1 at 850" F. and U J o ~ oStpan1 Average of all determinations
Since these experiments mere conducted under nonequilibrium conditions, it is expcctcd t h a t the extent of reaction will depend upon duration of heating, flovv conditions, diffusion rates, and thermal considerations influencing the separation of the reacting groups. Additionally, for the case of steam treatment, there is
July 1949
1489
INDUSTRIAL AND ENGINEERING CHEMISTRY
superimposed on these the factor of steam concentration in the heating atmosphere. I n air as a medium, thermal vibration of sufficient amplitude to bring two hydrogen ions simultaneously into collision with a structural oxygen atom or a hydrogen ion in contact with a n hydroxyl ion group is necessary for a reaction of type 9 to occur. The formation of hydronium iop resulting from the introduction of steam enlarges the sphere of possible reactivity by superimposing on the area of thermal vibration a spreading effect depending upon the extent of water adsorption and corresponding in value to the dimensions of water molecules. Thus, it is reasonable to expect that, up to the limit imposed by complete saturation of hydrogen ion t o form hydronium ion and spatial considerations influenced by thermal vibration, a greater degree of reaction takes place with increasing steam concentration. Gpon saturation of all of the hydrogen ion with water, no further effect should be expected from increased steam concentration a t any one temperature. This is in agreement with the experimental facts. The removal of hydrogen ion by combination with structural oxygen atoms or hydroxyl groups in montmorillonite reduces the negative charge existing upon the structure from which is derived the base exchange properties responsible for the presence of hydrogen ion in the first place, If the hypothesis postulated above is correct, then it points to the hydrogen ion being in an essentially nonhydrated state after the clay catalyst has been heated to 1050" F. or higher in air. This appears to be very likely because if hydronium ion already existed in the structure of montmorillonite and could be maintained a t these elevated temperatures without the presence of water vapor in the surrounding atmosphere, then the addition of steam to the atmosphere in contact with the heated samples would not influence the degree of hydrogen ion removal. Support for this viewpoint appears in the statement ( 1 ) that removal of interplanar water is accomplished a t a temperature of about 392 O F. and further that the significant ignition losses occurring in montmorillonite clays from 752" to 1112' F. result possibly from the elimination of hydroxyl as water ( 1 ) . CORRELATION O F HYDROGEN ION CONTENT WITH X-RAY DIFFRACTION RESULTS
As pointed out above, the decomposition point of montmorillonite clay calculated from the empirical relationship between hydrogen ion concentration and temperature of air calcination is in agreement with that obtained by the x-ray method. In the previous paper on x-ray diffraction studies of Filtrol clay catalyst (2), it was shown that a decrease in relative line intensities of the montmorillonite pattern occurred with increased temperature of heating in both air and steam mediums but that isothermally the effect on line intensities of increased steam concentration was not so marked. Some evidence will now be presented to show that the reduction in line intensities is apparently connected with the removal of hydrogen ion. I n Table VII, A , B , C, respectively, data are given for the degree of hydrogen ion removal as a function of calcination temperature in air, in steam, and as a function of steam concentration at a particular temperature. The large changes in the concentration of this ion produced by heating over the temperature interval shown in parts A and B of this table are readily correlated with the changes in line intensities for the same interval listed in Tables IV and V of t h e previous paper (8). Thus, for air heating over the range 1050" to 1400" F., catalyst batch H-264 with a change in hydrogen ion of 62% shows a change in the relative intensity of the long spacing reflection from strong to medium strong. For 0% (air heating), 12 and 100% steam treatment over the interval 1100" to 1400' F., the percentage change in hydrogen ion for catalyst H-208 was 48, 57, and 71, respectively, with decreases in line intensity from strong to medium strong, t o somewhat under medium strong, to weak, respectively. Part C of Table VI1 shows that, for the 1100" F. isotherm, increasing the concentration of steam from 0% to 100% effected only a 20%
decrease in hydrogen ion, while a t 1400" F. the effect amounted to 55%. With the smaller change in hydrogen ion, no noticeable change in line intensity was observed, but the large change in hydrogen ion content was accompanied by an intensity drop from medium strong to weak.
TABLEVII. ION
CORRELATION BETWEEN DEGREE OF HYDROGEN DECREASE I 3 S-R-lY INTENSITIES
REMOVAL AND A.
Batch
Temp., ' F.
H-204
I050 1400
H-208
1475 1100 1400 1436
E.
Air Heated Ramplee
CH-. Mole/Rp.a 0.204 0.078 0.061 0.130 0,067 0.041
%, A C H ? \, , . -..
, i62o ?
1
)2i
Intensity 10 .I.Lineb
me vvf
4j: 1 ' '
ms 139 i\' Steam Treated Samples, Batch H-20S, as Function of Temperature
Steam Conon.,
%
12
Temp,
CH %, ACE'
Intensity 10 i. Linec
1100
Mole/K,a.n 0.116 0,050 0.104 0.030
5i
ms-
1100 1400
F. 1400
100
68
..
71 m Steam Treated Samples, Batch H-208. ns Function of Steam Concentration 0 1100 0.130 12 0.116 i i 1:: 100 0.104 J 20 I10 0 1400 0,067 ms 12 0.050 2s me100 0 030 J 55 j40 .v 0 Data from Table V, this paper. b Data from Table I V , previous paper ( 2 ) . s = strong, m = medium, v = very, f = faint, w = weak. 0 Data from Table V, previous paper ( 2 ) .
C.
\
1'"''
Evidently, as shown by Table VII, for a sufficient change t o occur in line intensity t o be verified by visual estimation, there must be a fairly large change in hydrogen ion cont'ent. Another factor which may enter into the detection of line intensity change is that the intensity appears to change more rapidly above 1400' F. where the hydrogen ion concentration is low already and any further reduction is percentagewise a large one. This is readily seen from the data in Table VII. With the effect of steam superimposed upon that of temperature, this fact.or is operative even a t 1400" F. for the case of steam treated samples. I n a forthcoming paper, experimental evidence will be presented to demonstrate the existence of a relationship betn-een the concentration of hydrogen ion and catalytic cracking activit,y for Filtrol clay catalyst subjected to various heat treatmenu. purther correlations with the x-ray diffraction data reportpd previously will be given. ACKNOW LEDGJIESTf
The author wishes t o thank the management of the Union Oil Company for permission to publish this research, H. C. Huffman for some helpful suggestions, Mrs. Juanita 31. Cartmel for assi&ance with the experimental work, and G. IT-. Hendricks and N. L. Kay for sample preparations. LITERATURE CITED
(1) Bradley, W. F., J. Am. Chem. Soc., 67, 980 (1945). (2) Grenall, A., IND.ENCI. CHEM.,40, 2148 (1948). (3) Grim, R. E., and Rowland, R. A., J . Am. Ceram. Soc., 27, 65 (1944). (4) Hansford, R. C., IND.ENG.CHEM.,39,849 (1947). (5) Turkevich, J., and Smith, R. K., Nature, 157,874 (1946). R ~ C E I V EDecember D 15, 1947. Presented before the Joint Meeting of the Electron Microscope Sooiety of America, the American Society for X-Ray and Electron Diffraotion, Mellon Institute, and the University of Pittsburgh, December 5, 6,and 7, 1946, Pittsburgh, Pa.
