fore we can consider that the experimentally observed equality of the numbers of B centers on the original and regenerated catalysts is evidence that there is no change in the zeolite lattice during operation of the catalyst. Thus we see that the zeolite present in this hydrocracking catalyst does not undergo any structural changes in 320 h of operation. LITERATURE CITED i. 2. 3. 4.

5. 6. 7. 8. 9.

B. Peralta, C. P. Reeg, R. P. Vaell, et al., Chem. Eng. Proc., 58, 41-49 (1967). G. D. Chukin and L. A. Ignat'eva, Zh. Prikl. Spektrosk., 13, No. I, 89-95 (1970). K. I. Zimina, B. V. Smirnov, and G. D. Chukin, in: Automation and Control and Measuring Instruments [in Russian], No. 9, TsNllTEneftekhim, Moscow (1973), pp. 25-29. E. M. Flanigen, N. Khatami, and M. A. Szumanski, in: Molecular Sieve Zeolites (Advances in Chemistry Series, No. I01), American Chemical Society, Washington, D. C. (1971), pp. 201219. G. D. Chukin and B. V. Smirnov, Zh.. Fiz. Khim., 50, No. i, 141-145 (1976). A. V. Kiselev and V. I. Lygin, Infrared Spectra of Surface Compounds [in Russian], Nauka, Moscow (1972). G. D. Chukin and B. V. Smirnov, Dokl. Akad. Nauk SSSR, 226, No. 6, 1370-1373 (1976), G. D. Chukin and B. V. Smirnov, Zh. Strukt. Khim., 19, No. i, 96-102 (1978), G. D. Chukin and B. V. Smirnov, Zh. Strukt. Khim., 19, No. 3, 480-487 (1978).

PREPARATION OF SELECTIVE HYDROCRACKING CATALYST FOR SERVICE V. V. Shipikin, V. Yu. Georgievskii, V. N. Brovko, A. B. Rozenblut, and I. N. Tolkacheva

UDC 541.183:665.664.2

A process that has come into commercial use in recent years as a means of raising the octane number of gasolines is selecgive hydrocracking, whic~ consists of selective cracking of the low-octane n-paraffins present in naphthas [1-3]. This process uses bifunctional catalysts, of which the most important are certain geometrically selective zeolites [4] such as chabazite, erionite, and gmelinite. The hydrogenating component is usually a Group VI or VIII metal [5-8]. The catalyst of the greatest interest is based on erionite with molybdenum trioxide as the hydrogenating component. This catalyst is usually prepared by mixing erionite with an aluminum hydroxide binder containing the hydrogenating component; this mixture is then molded, and the granules are dried and calcined [9], Before use, the catalyst is subjected to hightemperature, high-pressure reduction withhydrogen-rich gas. In this connection, it h a s b e e n of interest to investigate the influence of the catalyst calcination and reduction conditions on its catalytic properties. In the present work, catalytic properties were investigated in a high-pressure pilot unit with recirculation of hydrogen-rich gas [i0]. The feed and the liquid and gaseous reaction products were analyzed chromatographically. The catalyst activity was rated on the basis of the degree of conversion of n-paraffins; the selectivity was defined as the ratio of the quantity of n-paraffins reacted to the total quantity of hydrocarbons of all classes subjected to hydrocracklng. The feedstock was a rafflnate with the following characteristics:

Density, kg/m) Disdlla~on, ~C IBP 10 % 50 % 90 % EP

694 ?1 74 81 106 122

Hydrocarbon composition, wt. % aromatics 11,2 naphthenes 9A paraffins . 79+4 n-hexanc 20,,9 a-heptanc 10.0

Scientific/Industrial Association "Lenneftekhim." Industrial Association "Kirishinefteorgsintez." Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 7-8, June, 1982. 266

0009-3092/82/0506-0266507.50

9 1983 Plenum Publishing Corporation

gO

45#

55g

500

F~O

Temperature, *C Fig. i. Activity (continuous curve) and selectivity (dashed curve) as functions of calcination temperature. TABLE I

Index

tca Hydrocracking onat taol~stcalcined 550 C in indicated me_.~dium __9 flue a~ gas

Yield, wt. % gas liquid product

25,3/30,9 24,5/28,9 74,7/69,1 i 75,5/71 ~i

Convemion of paralytic hydrocarbons,wt.

9o

79,0/90,~ 88,2/74,8 88,8/91,t [ 82,2/87,5 82,1/91,I ] 72,4/78,6 n -Csq-n-C~ 0/4,2 I 4,0/8,6 iso-C6 + iso-C~ Seleetivi~ of 100190,~ 91,0/83,7 catalyst,~o n -C~ n-C7

.

_ _

9

-

Notes. i) Process conditions: pressure 2 MPa, feedstock space velocity 2 h -~, hydrogen-rich gas circulation ratio (NTP) i000 m3/m 3 feed; feedstock was a raffinate from benzene/toluene production. 2) First value shown is for hydrocracking at 380~ second value at 400=C=

The catalyst was calcined in air at atmospheric pressure, at a temperature selected within the range 450-600~ In Fig. 1 we show the activity and selectivity of the catalyst as functions of the calcination temperature. It will be noted that the highest catalytic activity corresponds to a 520-550~ calcination temperature. Increases in calcination temperature above this point led to a slight decrease in catalyst activity. The catalyst selectivity increased as the calcination temperature was increased from 450 ~ to 550~ and then remained very nearly unchanged when the temperature was further increased to 6000C. Apart from the calcination temperature, the medium in which the catalyst is calcined had a great influence on the catalytic properties (Table i). Under identical hydrocracking conditions, the n-paraffin conversion on a catalyst calcined in a flue gas medium was lower than on a catalyst calcined in air. The calcination medium had an even greater effect on the selectiv267

85 ~.75

Temperamre,*C Fig. 2. Influence of reduction temperature on catalyst selectivity. TABLE 2

Index

Hydtocracking on catalystreduced at 800~ underindicated pressure,MPa 2

Yie1 wt liqui p od ct

4

8

l

19,2 13,9 15580,8 86,1

Conversion of nparaffins, wt. % 67,0 60,3 44,0 C6 Cv 75,0 66,0 47,0 62,0 45,0 C6+C7 CatalystselectivIO0 I00 ity.%

Note. Hydrocracking conditions: temperature 380~ pressure 2 MPa, feedstock space velocity 2 h-*, hydrogen-rich gas circulation ratio (NTP) i000 ms/m s feed. ity of the catalyst. Catalysts calcined in flue gas were considerably lower in selectivity than those calcined in air, but were less sensitive to the process temperature. Thus, the erionite-containing catalyst must be calcined in ai~ at temperatures of 520550=C in order to ensure high activity and selectivity. In these studies, the catalyst was reduced directly in the reactor of the pilot unit for 4 h with a hydrogen-rich gas circulation ratio of I000 m3/m 3. The influence of the reduction temperature was investigated with the hydrogen-rich gas pressure constant at 2 MPa in all runs, It was established that higher reduction temperatures gave lower catalyst activities (Fig. 2). The catalyst reduced at 380~ gave an 80.1% conversion of n-paraffins, whereas the catalyst reduced at 530~ gave only 61.1%. The greatest dmop in activity was noted when the reduction temperature was raised above 450~ For example, an increase of the reduction temperature from 3800C to 4500C lowered the n-paraffin conversion by only 3.5% by weight, in comparison with a 14.9% decrease in conversion when the reduction temperature was raised from450 to 530~ The catalyst selectivity was not affected appreciably by changes of the reduction temperature within the range investigated; the selectivity was 100% in all cases. The influence of the hydrogen-rich gas pressure in the catalyst reduction on its catalytic properyies was investigated at reduction temperatures of 380" and 500~ varying the pressure from 2 to 8 MPa. It was found that with a reduction temperature~ 380oC, increases in pressure, within the indicated limits, had practically no effect on the catalyst activity or selectivity. A different picture was observed at a 500"C catalyst reduction temperature (Table i)~, where increases in pressure gave catalysts with considerably lower activities. From these results, we can draw the firm conclusion that in order to obtain high-activity

268

catalysts, the reduction should be performed at 380~400~ working pressure of the process.

at a pressure no higher than the

LITERATURE CITED i. 2. 3. 4. 5. 6. 7. 8. 9. i0.

No J. Chen, G. Maziuk, and A. B. Schwartz, Oil Gas J., No. 47, 154-157 (1968). Hydrocarbon Process., No. 5, 97 (1972). M. M. Kukovitskii, N. P. Dagaev, et al., Neftepererab. Neftekhim., No. 9, 29-31 (1978). J. N. Miale, N. J. Chert, and P. B. Weisz, J. Catal., No~ 2, 278-287 (1966). U. S. Pat. 3,344~058. U. S. Pat. 3,379,640. Fr. Pat. 1,580,689. Fr. Pat. 2,080,014. USSR Inventor's Certificate 562,309. N. R. Bursi&n and G. N. Maslyanskii, Khim. Tekhnol. Topl. Masel, No. I0, 6-9 (1961) o

EFFECT OF HEAT TREATMENT ON ADSORPTIVE AND CATALYTIC PROPERTIES OF SUPERHIGH-SILICA ZEOLITES V. Yu. Volkov, M. A. Kaliko, B. A. Lipkind, and V. V. Zadymov

UDC 665.644.2.097.3:661.183.6

Major attention is being given today to the properties and catalytic applications of superhigh-silica (SHS) zeolites (ZSM type). These zeolites can be used in formulating catalysts for various petroleum refining processes [1-7], but the information available on their hightemperature stability is contradictory. Here we are reporting on a study of the effect of heat treatment on certain properties of SHS zeolites. The samples used in this study (Table !) were obtained by various methods. The TsVK-I zeolite, synthesized using tetrabutylammonium, is the most similar to Type ZSM-II zeolite in the structure of its crystal lattice. The TsVK-XI sample was synthesized using an organic base that did not contain nitrogen, and the TsVM was synthesized without any organic base. Both of these latter zeolites are most similar in their characteristics to Type ZSM-5 zeolite. The SHS zeolites, the same as the Type Y zeolite that is used extensively in catalysis, were subjected to activation to remove sodium (ion exchange). Before activation, the TsVK-I and TsVK-XI zeolites were calcined in air at 500-550~ to remove the organic bases that had been introduced dur~ig the synthesis. The samples were treated with an ammonium sulfate solution, concentration 20-30 g/liter, at a ratio (NH4)aSO4:Na~O = 5:1 (g-eq), for 2 h at 2060~ The treatment was repeated 2-4 times, depending on the required content of Na20, washTABLE I

~

Index SiO~: AI~O3 mole ratio S{atic Capacity for vapor, cm3/g H20 (p/P/s= 0',1) CsH6 (p~gs~0,4) C-H16 (P/ps=0,4) C~H~2 (pips=O,4) Degree of crystallinity, %

i

VK- TsVK- TsVM XI 62

41

33

0,06 0,t6 0,22

0,05 0,11 0,15

0,08 0,13 0,18 0,10 95

o,,6 o# 100

Notation: p is the pressure of the adsorbate vapor under the conditions of experiment; Ps is its saturated vapor pressure.

Gorki Experimental Plant. All-Union Scientific-Research Institute for Petroleum Processing (VNII NP). Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 8-10, June, 1982. 0009-3092/82/0506-0269507.50

<~ 1983 Plenum Publishing Corporation

269