Abstract:
A method of simultaneously producing or co-synthesizing a combination of zeolite X and zeolite A by separately preparing a sodium aluminate solution and a sodium silicate solution and reacting the solutions in the presence of a small amount of zeolite X seed under controlled conditions of temperature and time to form a product which is a combination of zeolite X and zeolite A.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     In general, the present invention relates to the production of zeolites. 
     2. Description of the Prior Art 
     Certain naturally occurring hydrated metal aluminum silicates are called zeolites. The synthetic zeolites of the invention have compositions similar to some of the natural zeolites. The most common of these zeolites are sodium zeolites. 
     Zeolites consist basically of a three-dimensional framework of SiO 4  and AlO 4  tetrahedra. The tetrahedra are cross-linked by the sharing of oxygen atoms so that the ratio of oxygen atoms to the total of the aluminum and silicon atoms is equal to two or O/(Al+Si)=2. The electrovalence of each tetrahedra containing aluminum is balanced by the inclusion in the crystal of a cation, for example, a sodium ion. This balance may be expressed by the formula, Al/Na=1. The spaces between the tetrahedra are occupied by water molecules prior to dehydration. 
     Zeolites may be activated by heating to effect the loss of the water of hydration. The dehydration results in crystals interlaced with channels of molecular dimensions that offer very high surface areas for the adsorption of foreign molecules. The interstitial channels of zeolite X are of a size such that heptacosafluorotributylamine and larger molecules will not enter into the channels. The interstitial channels of zeolite A will not accept molecules larger than 5.5 A. 
     Zeolites A and X may be distinguished from other zeolites and silicates on the basis of their x-ray powder diffraction patterns and certain physical characteristics. The x-ray patterns for several of these zeolites are described below. The composition and density are among the characteristics which have been found to be important in identifying these zeolites. 
     The basic formula for all crystalline sodium zeolites may be represented as follows: 
     Na 2  O:Al 2  O 3  :xSiO 2  :yH 2  O 
     In general, a particular crystalline zeolite will have values for x and y that fall in a definite range. The value x for a particular zeolite will vary somewhat since the aluminum atoms and the silicon atoms occupy essentially equivalent positions in the lattice. Minor variations in the relative numbers of these atoms do not significantly alter the crystal structure of physical properties of the zeolite. For zeolite X, an average value for x is about 2.5 with the x value normally falling within the range 2.5±0.5. For zeolite A, the x value normally falls within the range 1.85+0.5. 
     The value of y is not necessarily an invariant for all samples of zeolites. This is true because various exchangeable ions are of different size, and, since there is no major change in the crystal lattice dimensions upon ion exchange, the space available in the pores of the zeolite to accommodate water molecules varies. 
     The average value for y determined for zeolite X is 6.2. For zeolite A, it is 5.1. 
     In zeolites synthesized according to the preferred procedure, the molar ratio Na 2  O/Al 2  O 3  should equal one. But if all the excess sodium present in the mother liquor is not washed out of the precipitated product, analysis may show a ratio greater than one, and if the washing is carried too far, some sodium may be ion exchanged by hydrogen, and the ratio will drop below one. It has been found that due to the ease with which hydrogen exchange takes place, the ratio for zeolite X lies in the range of 
     
         Na.sub.2 O/Al.sub.2 O.sub.3 =0.9±0.2. 
    
     The ratio for zeolite A lies in the range of 
     
         Na.sub.2 O/Al.sub.2 O.sub.3 =1.0±0.2. 
    
     Thus, the formula for zeolite A may be written as follows: 
     1.0±0.2Na 2  O:Al 2  O 3  :1.85±0.5SiO 2  :yH 2  O 
     The formula for zeolite X may be written as follows: 
     0.9±0.2Na 2  O:Al 2  O 3  :2.5±0.5SiO 2  :yH 2  O 
     &#34;y&#34; May be any value up to 6 for zeolite A; any value up to 8 for zeolite X. 
     The pores of zeolites normally contain water. 
     The above formulas represent the chemical analysis of zeolites A and X. When other materials as well as water are in the pores, chemical analysis will show a lower value of y and the presence of other adsorbates. The presence in the crystal lattice of materials volatile at temperatures below about 600° C. does not significantly alter the usefulness of the zeolites as an adsorbent since the pores are usually freed of such volatile materials during activation. 
     Among the ways of identifying zeolites and distinguishing them from other zeolites and other crystalline substances, the X-ray powder diffraction pattern has been found to be a useful tool. In obtaining the X-ray powder diffraction patterns, standard techniques are employed. The radiation is the Kα doublet of copper, and a Geiger counter spectrometer with a strip chart pen recorder is used. The peak heights, I, and the positions as a function of 2θ where θ is the Bragg angle, were read from a spectrometer chart. From these, the relative intensities, 100 I/I o , where I o  is the intensity of the strongest line or peak, and d the interplanar spacing in A corresponding to the recorded lines were calculated. 
     X-ray powder diffraction data for sodium zeolite X are given in Table A. 100 I/I o  and the d values in angstroms (A) for the observed lines for zeolite X are also given. The X-ray patterns indicate a cubic unit cell of dimensions between 24.5 A and 25.5 A. In a separate column are listed the sum of the squares of the Miller indices (h 2  +k 2  +l 2 ) for a cubic unit cell that corresponds to the observed lines in the x-ray diffraction patterns. The a o  value for zeolite X is 24.99 A where a o  is the unit cell edge. 
     Zeolite X is a name given to a synthetic zeolite having the crystal structure of the naturally occurring mineral, faujasite. Zeolite X is the name for those compounds having an SiO 2  /Al 2  O 3  ratio of less than 3. 
     
                       TABLE A______________________________________X-RAY DIFFRACTION PATTERN FOR ZEOLITE X h.sup.2 + k.sup.2 + l.sup.2             ##STR1##                      d (A)______________________________________3                100      14.478                18       8.8511               12       7.5419               18       5.7327               5        4.8132               9        4.4235               1        4.2340               4        3.94643               21       3.80844               3        3.76548               1        3.60951               1        3.50056               18       3.33859               1        3.25367               4        3.05172               9        2.94475               19       2.88580               8        2.79483               2        2.74388               8        2.66391               3        2.62096               1        2.550108              5        2.404123              1        2.254128              3        2.209131              3        2.182136              2        2.141139              2        2.120144              1        2.083164              1        1.952168              1        1.928184              1        1.842195              1        1.789200              2        1.767211              3        1.721243              3        1.603______________________________________ 
    
     The more significant d values for zeolite X are given in Table B. 
     
                       TABLE B______________________________________MOST SIGNIFICANT d VALUES FOR ZEOLITE Xd Value of Reflection in A______________________________________14.42 ± 0.28.82 ± 0.14.41 ± 0.053.80 ± 0.053.33 ± 0.052.88 ± 0.052.79 ± 0.052.66 ± 0.05______________________________________ 
    
     X-ray powder diffraction data for sodium zeolite A are given in Table C. 
     
                       TABLE C______________________________________X-RAY DIFFRACTION PATTERN FOR ZEOLITE A h.sup.2 + k.sup.2 + l.sup.2             d (A)                     ##STR2##______________________________________1                12.29   1002                8.71    703                7.11    354                6.15    25                5.51    256                5.03    28                4.36    69                4.107   3510               3.895   211               3.714   5013               3.417   1614               3.293   4516               3.078   217               2.987   5518               2.904   1020               2.754   1221               2.688   422               2.626   2024               2.515   625               2.464   426               2.414   &gt;127               2.371   329               2.289   130               2.249   332               2.177   733               2.144   1034               2.113   335               2.083   436               2.053   941               1.924   742               1.901   444               1.858   245               1.837   349               1.759   250               1.743   1353               1.692   654               1.676   255               1.661   257               1.632   459               1.604   6______________________________________ 
    
     The more significant d values for zeolite A are given in Table D. 
     
                       TABLE D______________________________________MOST SIGNIFICANT d VALUES FOR ZEOLITE Ad Value of Reflection in A______________________________________12.2  ± 0.28.7  ± 0.27.10 ± 0.155.50 ± 0.104.10 ± 0.103.70 ± 0.073.40 ± 0.063.29 ± 0.052.98 ± 0.052.62 ± 0.05______________________________________ 
    
     Occasionally, additional lines not belonging to the pattern for the zeolite appear in a pattern along with the X-ray lines characteristic of that zeolite. This is an indication that one or more additional crystalline materials are mixed with the zeolite in the sample being tested. Frequently these additional materials can be identified as initial reactants in the synthesis of the zeolite, or as other crystalline substances. When the zeolite is heat treated at temperatures of between 100° C. and 600° C. in the presence of water vapor or other gases or vapors, the relative intensities of the lines in the X-ray pattern may be appreciably changed from those existing in the unactivated zeolite patterns. Small changes in line positions may also occur under these conditions. These changes in no way hinder the identification of these X-ray patterns as belonging to the zeolite. 
     The particular X-ray technique and/or apparatus employed, the humidity, the temperature, the orientation of the powder crystals and other variables, all of which are well known and understood to those skilled in the art of X-ray crystallography or diffraction can cause some variations in the intensities and positions of the lines. These changes, even in those few instances where they become large, pose no problem to the skilled X-ray crystallographer in establishing identities. Thus, the X-ray data given herein to identify the lattice for a zeolite are not to exclude those materials which, due to some variable mentioned or otherwise known to those skilled in the art, fail to show all of the lines, or show a few extra ones that are permissible in the cubic system of that zeolite, or show a slight shift in position of the lines, so as to give a slightly larger or smaller lattice parameter. 
     A simple test described in &#34;American Mineralogist&#34;, Vol. 28, page 545, 1943, permits a quick check of the silicon to aluminum ratio of the zeolite. According to the description of the test, zeolite minerals with a three-dimensional network that contains aluminum and silicon atoms in an atomic ratio of Al/Si=2/3=0.67, or greater, produce a gel when treated with hydrochloric acid. Zeolites having smaller aluminum to silicon ratios disintegrate in the presence of hydrochloric acid and precipitate silica. 
     U.S. Pat. No. 2,882,243 describes a process for making zeolite A comprising preparing a sodium-aluminum-silicate water mixture having an SiO 2  /Al 2  O 3  mole ratio of from 0.5:1 to 2.5:1, an Na 2  O/SiO 2  mole ratio of from 0.8:1 to 3:1, and an H 2  O/Na 2  O mole ratio of from 35:1 to 200:1, maintaining the mixture at a temperature of from 20° C. to 175° C. until zeolite A is formed, and separating the zeolite A from the mother liquor. 
     U.S. Pat. No. 2,882,244 describes a process for making zeolite X comprising preparing a sodium-aluminum-silicate water mixture having an SiO 2  /Al 2  O 3  mole ratio of from 3:1 to 5:1, an Na 2  O/SiO 2  mole ratio of from 1.2:1 to 1.5:1, and an H 2  O/Na 2  O mole ratio of from 35:1 to 60:1, maintaining the mixture at a temperature of from 20° C. to 120° C. until zeolite X is formed and separating the zeolite X from the mother liquor. 
     The process described in U.S. Pat. No. 3,101,251 is similar to that described in U.S. Pat. Nos. 2,882,243 and 2,882,244, except that the reaction mixture contains an admixture of non-kaolinitic alumino-silicate mineral and sodium hydroxide that has been fused at a temperature of between 330° C. and 370° C. 
     In U.S. Pat. No. 3,119,659, a kaolin clay and sodium hydroxide are formed into a compact body, dried, reacted in an aqueous mixture at a temperature of from 20° C. to 175° C. until a zeolite is formed. Zeolite A is formed in a reaction mixture having an Na 2  O/SiO 2  molar ratio of 0.5:1 to 1.5:1, an SiO 2  /Al 2  O 3  molar ratio of 1.6:1 to 2.4:1 and an H 2  O/Na 2  O molar ratio of 20:1 to 100:1. Zeolite X is formed in a reaction mixture having an Na 2  O/SiO 2  molar ratio of 1.5:1, an SiO 2  /Al 2  O 3  molar ratio of 5:1, and an H 2  O/Na 2  O molar ratio of 30:1 to 60:1. 
     U.S. Pat. No. 4,235,856 discloses a process for making a combination of zeolite X and zeolite A wherein a sodium aluminate solution is added to a sodium silicate solution to form a mixture, then heating and reacting the mixture to 80°-120° C. until the combination zeolite is formed. 
     Another patent which discloses a process for making synthetic zeolite particles having two different sized effective pore entrance diameters within a single particle, namely a particle containing both a Type A zeolite structure and a Type X zeolite structure is U.S. Pat. No. 3,366,578. 
     U.S. Pat. No. 4,094,778 discloses a process for sequestering calcium and magnesium cations using mixtures of zeolite A and zeolite X. 
     British Pat. No. 1,533,496 sets forth a process for preparing low silica faujasite-type zeolites by adding potassium hydroxide or a potassium salt to the alumina trihydrate in addition to the sodium hydroxide prior to the addition of the sodium silicate. 
     U.S. Pat. No. 4,166,099 discloses a method for preparing crystalline aluminosilicates, such as a Type X synthetic faujasite by seeding an alkaline precursor mixture of alumina and silica with small size zeolite seeds having an average particle size below about 0.1 micron. 
     Zeolites are useful as molecular sieves and as sequestering agents for calcium and magnesium cations. They are particularly useful in detergent or washing compositions. 
     It is a primary object of the present invention to provide a faster and more economical process for making combination zeolite X and zeolite A particles. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method of simultaneously producing or co-synthesizing a combination of zeolite X and zeolite A. A sodium aluminate solution and a sodium silicate solution are separately prepared. These solutions are then reacted in the presence of a small amount of zeolite X seed under controlled conditions of temperature and time to form a product which is a combination of zeolite X and zeolite A. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In general, solutions of sodium aluminate and sodium silicate are separately prepared. These solutions are mixed together at a temperature of about 15° C. in the presence of a small amount of seed zeolite. As soon as addition has been completed, the mixture is rapidly heated to a temperature of about 90°-100° C. and held at such temperature for about 45 minutes. The mixture is then cooled to a temperature of about 70°-75° C. and cooked or held at such temperature for about three to four hours. The hot product is transferred to a holding container and subsequently filtered out at a temperature of about 65°-75° C. After washing and drying, a product which is a combination of zeolite X and zeolite A is recovered. 
     The compositions of the sodium aluminate and the sodium silicate may be varied as desired; however, they should be such as to provide a system having a composition of (3.0-5.5) Na 2  O 2  Al 2  O 3 .(2.5-4.5)SiO 2 .(100-120)H 2  O. For example, a sodium aluminate solution comprising 9.55 percent sodium and 4.48 percent aluminum and a sodium silicate solution of water, sodium hydroxide and sodium silicate of 9.85 percent sodium and 11.90 percent silicon have produced excellent yields. 
     The seed zeolite may be a commercially available zeolite X or a combination of zeolite X and zeolite A or may be product from a previous run of the process of this invention. The latter is sometimes referred to as bulk product. The seed zeolite may be present in an amount of about 0.1 to 10 percent by weight of the total system. Activation of the seed zeolite may be from about one minute to about six hours, and the temperature may be from about 0° C. to about 110° C., with 15° C. being most preferred. Activation may be in the sodium silicate alone, a sodium silicate-sodium hydroxide mixture, or a sodium silicate-sodium hydroxide-water mixture. Activation may thus be separately performed or done in situ. 
     Preferably, the sodium aluminate solution is added to the sodium silicate solution. Such addition is relatively slow with vigorous stirring. The system is then allowed to gel without stirring at ambient temperature for up to about 24 hours. Gelling time may be as little as 15 minutes. Cooking time may be from about 1 hour to about 12 hours. 
    
    
     Having described the basic aspects of the invention, the following examples illustrate specific embodiments thereof. 
     General Procedure 
     All reactions were carried out in a 1-liter, 3-necked, round-bottom flask equipped with a Teflon blade stirrer operated by a variable speed electric stirrer. A thermometer was inserted in one neck of the flask. The sodium aluminate was added via a syringe pump through the final neck which was subsequently equipped with a condenser during heating and cooking periods. The system was cooled with a refrigerated circulating bath and heated with oil bottles on hot plates. 
     Filtrations were made with medium frit glass filter funnels. The solids were washed by stirring for 1 hour in 500 ml of distilled water. The washed solids were again filtered and the wash water combined with the spent liquor. The solids were dried at 115° C. in an oven set to shut off three hours after the solids were placed in the oven. The solids were removed after the oven had cooled to ambient temperature. Samples were ground with a mortar and pestle prior to Calcium Exchange Capacity (CEC) and Magnesium Exchange Capacity (MEC) measurement. 
     Reagents were commercially available products or prepared in the laboratory. Sodium silicate solution contained 6.6 percent sodium and 16.2 percent silicon. A typical analysis of sodium aluminate used was 9.7 percent sodium and 5.1 percent aluminum. Zeolite seed was bulk product from previous runs with the initial seed being a commercial zeolite X product, Linde 13X. 
     The recipe used was 100 g of sodium silicate and 5.7 g of contained seed (average 20 percent moisture). The amounts of sodium aluminate, sodium hydroxide and water were adjusted to provide a final system composition as follows: 
     4.4Na 2  O.Al 2  O 3 .3.0SiO 2 .150H 2  O. 
     Procedure except as otherwise noted was as follows: 
     The sodium silicate, sodium hydroxide, seed and water were mixed in the reactor and stirred at 200 rpm for 1 hour (seed activation period). 
     The 13° C. bath was contacted with the reactor and the stirrer turned up to 600 rpm (cool down period). 
     After 5 minutes, when the reactor temperature reached 15° C., the sodium aluminate was added. This period ranged from 7 minutes to 95 minutes and is described in Table I (mix period). 
     The condenser was put in place, the stirrer turned down to 200 rpm and a 110° C. oil bath contacted with the reactor. Heatup period ended when the reaction mass reached 90° C. and the cook period started. Typically, the system reached 102°-103° C. during cook. The heat-up period was typically 22-30 minutes. 
     For those experiments with a hold period, the stirrer was shut off, and the 110° C. oil bath was replaced with a 73° C. oil bath which maintained the reaction mass at 70° C. for the stated period of time. 
     The solids were filtered, washed, filtered again and dried. The above procedure is illustrated with the following specific examples. 
     EXAMPLE 1 
     100.0 g of sodium silicate, 5.7 g of seed, 10.4 g of NaOH and 232.1 g of water were placed in the reactor. After 1 hour of stirring at 200 rpm, the refrigerated bath was contacted and the stirrer was turned up to 500 rpm. After 5 minutes, 147.6 g of sodium aluminate was added using a 100 ml syringe and a Saya syringe pump model 355 set at 120* 0.1. The addition required 35 minutes. The stirrer was turned back to 200 rpm&#39;s, the condenser was put in place, and the 110° C. oil bath contacted. After 26 minutes, the system was at 90° C. After 4 hours, the unit was shut down, the slurry filtered, the solids washed, refiltered and dried (Run 37 of Table I and Table II). 
     EXAMPLE 2 
     The same quantities as in Example 1, and in general the same procedures, were used with the following exceptions. The sodium aluminate was added using 2 plastic, 60 ml syringes in series with the pump at 120* 1. This required 15 minutes. The cook period was 3/4 hour. The stirrer was then shut off and the 73° C. oil bath was contacted with the system. After 41/2 hours, the system was filtered and treated as above (Run 45 of Tables I &amp; II). 
     The significant results, as well as the times for the various steps, are given in Table I. The average product composition was 1.01 (±0.15) Na 2  O.Al 2  O 3 .2.37(±0.22)SiO 2 .(4-6)H 2  O. 
     The average material utilizations are 99% Al, 70-75% Si and 20-25% Na. 
     Similar runs were made using various systems. The results are shown in Table III. 
     
                                           TABLE I__________________________________________________________________________MIXED ZEOLITES X AND A   Seed Mix Mix Gel              Cook                  %   %       Total       ProductRun   From Temp.       Time           Time              Time                  Zeolite                      Zeolite Crystal-    WeightNo..sup.1   Run No.   (°C.)       (min)           (hr)              (hr).sup.3                  X.sup.2                      A    x/A                              linity                                   CEC                                      MEC (g)__________________________________________________________________________1  I    15  95  16 6   45  32   1.41                              77   314                                      211 55.42  II   15  95  16 6   0   &#34;Mostly&#34;                           -- --   -- --  74.93  1    15  95  16 6   30  30   1.00                              60   299                                      185 86.64  1    15  90  2  4   52  40   1.30                              92   279                                      160 58.45  1    15  90  0  4   42  34   1.24                              76   265                                      175 65.16  1    15  95  0  4   34  42   0.81                              76   264                                      141 60.67  4    15  50  0  0   A   --   -- --   -- --  109.58  4    15  50  0  0   A   --   -- --   -- --  110.09  3    15  35  0  0   A   --   -- --   -- --  92.710 I    15  40  0  0   A   --   -- --   -- --  111.811 I    15  95  0  0   A   --   -- --   -- --  104.212 I    15  95  16 6   39  35   1.11                              74   246                                      162 57.413 12   15  95  0  4   29  34   0.54                              83   288                                      138 54.814 12   15  35  0  4   40  42   0.95                              82   278                                      175 70.415 12   15  30  0  0   A   --   -- --   -- --  101.216 4    15  35  0  4   43  16   2.69                              59   170                                      111 50.417 4    15  15  0  4   49  32   1.53                              82   172                                      127 56.418 4    15  15  0  1   35  28   1.25                              63   171                                      144 53.819 4    15  7   0  1   46  23   2.00                              69   233                                      147 54.720 4    20  7   0  1   40  17   2.34                              57   -- --  52.121 4    15  7   0  1   23   0   -- --   -- --  46.622 4    16  7   0  1/2 A   --   -- --   -- --  60.723 4    15  7   0  1/2 A   --   -- --   -- --  99.924 14   15  17  0  1   21  29   0.72                              50   216                                      102 51.925 14   15  15  0  1   18  40   0.45                              58   208                                      102 50.226 14   15  35  0  1   3   27   0.11                              30   155                                       72 51.727 5    15  35  0  4   H   --   -- --   -- --  74.628 5    15  35  0  4   H   --   -- --   -- --  78.029 5    15  35  0  4   H   --   -- --   -- --  81.830 5    15  35  0  4   H   --   -- --   -- --  79.831 5    15  35  0  4   H   --   -- --   -- --  79.932 20   15  35  0  4   H   --   -- --   -- --  54.533 20   15  35  0  4   H   --   -- --   -- --  54.734 1    15  35  0  4   32  38   0.84                              70   220                                      110 56.535 14   15  35  0  4   27  43   0.63                              70   209                                       98 53.436 14   15  35  0  4   32  41   0.78                              73   234                                      123 56.237 14   15  35  0  4   27  45   0.60                              72   237                                      117 58.838 14   15  35  0  4   31  43   0.72                              74   234                                      127 59.439 14   15  35  0  4   33  47   0.70                              80   236                                      122 57.140 5    15  35  0  4   36.sup.4                      44   0.82                              80   240                                      133 58.941 14   15  35  01 .sup. 2.sup.5                  33  44   0.75                              77   249                                      144 57.542 36.sup.6   15  35  0  .sup. 2.sup.5                  H   --   -- --   -- --  59.443 36.sup.6   15  35  0  .sup. 2.sup.5                  H   --   -- --   -- --  59.944 12   15  35  0  .sup. 1.sup.7                  40  53   0.75                              93   265                                      146 60.145 12   15  35  0  .sup. 3/4.sup.9                  32  49   0.65                              81   288                                      154 60.646 12.sup.9   15  35  0  .sup. 2.sup. 5                  26  38   0.68                              64   237                                      127 59.747 12.sup.9   15  35  0  .sup. 2.sup.5                  22  50   0.44                              72   242                                      113 58.848 Comm.   15  35  0  4   45  33   1.36                              88   242                                      125 63.4   Zeo. Y__________________________________________________________________________ .sup.1 Unless indicated in Table F, the seed is second generation, the seed quantity is 5.7 grams and the seed activity procedure is stir in N.sub.a OH + H.sub.2 O + SS for 1 hour. (SS = Sodium Silicate). .sup.2 All experiments prior to Run No. 14 corrected for change in X standard. A = Amorphous; H = Harmotome. .sup.3 Approximate 30 minutes heatup time. .sup.4 19% Harmotome. .sup.5 Held at 70° C. without stirring for an additional 3 hours. .sup.6 Slurry prepared, never filtered or dried. Run No. 36 was seed for this preparation. .sup.7 As 7 except held 4 hours. .sup.8 As in 7 except held 41/2 hours. .sup.9 Slurry prepared, never filtered or dried. Run No. 12 was seed for this preparation. 
    
     
                       TABLE II______________________________________               Seed       Seed ActivationRun No.  Seed Generation               Quantity (g)                          Procedure______________________________________1      0                       100 g SS for 3 hrs.2      2nd zeolite X           3 hour stir3      1st4      1st                     Overnight stir5      1st                     Overnight stir6      1st10     0                       100 g SS for 3 hrs.11     0                       100 g SS for 3 hrs.12     0                       100 g SS for 3 hrs.13     1st14     1st15     1st21                  0.622                  0.625                             5 min. stir26                  1.140                  2.8542     3rd                     None43     3rd46     3rd47     3rd                     None______________________________________ 
    
     
                                           TABLE III__________________________________________________________________________                Mix Seed           TotalRun                  Temp.                    %  %           Crystal-No. 1    System           (0° C.)                    13X                       ZB 100                           % X.sup.c                               % A.sup.c                                   linity                                        S/A                                           CEC                                              MEC__________________________________________________________________________1.  3.6 Na.sub.2 O.Al.sub.2 O.sub.3.3.0 SiO.sub.2.150 H.sub.2 O                15  .sup.a                       .sup.a                           87  13  100  6.69                                           259                                              1612.  3.0 Na.sub.2 O.Al.sub.2 O.sub.3.3.0 SiO.sub.2.100 H.sub.2 O                15  .sup.b                       .sup.b                           29   0  29   -- -- --3.  2.8 Na.sub.2 O.Al.sub.2 O.sub.3.3.0 SiO.sub.2.102 H.sub.2 O                15  100                        0  H   H   --   -- -- --4.  2.5 Na.sub.2 O.Al.sub.2 O.sub.3.3.0 SiO.sub.2.91.6 H.sub.2 O                15  41 59  45  34  79   1.32                                           240                                              1025.  2.5 Na.sub.2 O.Al.sub.2 O.sub.3.3.0 SiO.sub.2.91.6 H.sub.2 O                25  41 59  43 H                               43 H                                   --   -- -- --6.  2.3 Na.sub.2 O.Al.sub.2 O.sub.3.3.0 SiO.sub.2.91.6 H.sub.2 O                15  41 59  A   A   --   -- -- --7.  2.5 Na.sub.2 O.Al.sub.2 O.sub.3.3.0 SiO.sub.2.91.6 H.sub.2 O                15  41 59  44  32  77   1.38                                           240                                              128__________________________________________________________________________ .sup.a Previous bulk product from Run 12 of Table E. .sup.b Previous bulk product from Run 48 of Table E. .sup.c H = Harmotome; A = Armorphous Note: All used concentrated sodium aluminate, Al ˜ Na ˜ 13% Concentrated sodium silicate (Si ˜ 13%, Na ˜ 9%) was used in Runs 6 and 7. Cook time was 3/4 hour and hold time was 41/2 hours at 70° C. Runs No. 4-7 had ˜ 18% solids in slurry. 
    
     Not wishing to be bound by any particular theory, it is believed that there is a competition between seed induced growth of zeolite X and self-nucleation of zeolite A. If the temperature is lowered, the growth of zeolite X is favored at the expense of zeolite A and, conversely, if the temperature is increased, one rapidly enters a region where zeolite X will not grow on the seed. 
     The primary product upon completion of mixing is amorphous material, that is, the nuclei which may be crystalline consists of crystals too small to give an X-ray diffraction response. During the heat-up, cook and hold periods, material is transferred from the amorphous phase to the crystalline phases. This process is slow and requires at least 3/4 hour at cook temperature to insure a crystalline product. Considerably more time is required to make acceptable CEC and MEC product. 
     After a sufficient cook period to insure a crystalline product, the remainder of the time requirement is met with unstirred hold at 70° C. 
     Runs 1 through 21 demonstrate that a gel time is not necessary for the process. There appears to be a requirement for a cook period of about 3/4 hours. 
     Seed through the third generation was successfully used. Seed activation by contact with fresh sodium silicate for a period of time is required when using dry seed. 
     Mixing temperature is very important. Acceptable crystallinities can be achieved at higher mixing temperatures, but the magnesium exchange capacity suffers. 
     Reducing the cycle time decreases CEC and MEC. 
     Both CEC and MEC can be related to the sum of the mix, heat-up, cook and hold times (T) at the 99% statistical confidence levels by the following equations: 
     
         CEC(±9)=0.233*T(min)+170.3 
    
     and 
     
         MEC(±13)=0.143*T(min)+95.0. 
    
     Coulter counter product size distribution for Run No. 3 is given as follows: 
     
         ______________________________________Size μ   % Greater Than______________________________________1.0         1001.3         1001.6         922.0         762.6         603.2         494.0         425.1         376.3         328.0         2710.0        2012.8        1416.0        720.0        225.0        0.532.0        0.0______________________________________ 
    
     The mean size is 2.5μ. 
     The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the illustrated process may be made within the scope of the appended claims without departing from the spirit of the invention.