Catalysis Today(1997) Sugioka Et.Al


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Catalysis Today(1997) Sugioka Et.Al

  1. 1. i TDLS CTYS OAYI AAELSEVIER Catalysis Today 39 (1997) 61-67 Noble metals supported on mesoporous silicate FSM-16 as new hydrodesulfurization catalyst M. Sugioka*, L. Andalaluna, S. Morishita, T. Kurosaka Department of Applied Chemistry, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050, JapanAbstract The Pt supported on mesoporous silicate FSM-16 showed high and stable catalytic activity for the hydrodesulfurization ofthiophene at 350°C and this activity was higher than that of commercial CoMo/A120 3 catalysts. The acid sites of FSM-16 andthe spillover hydrogen formed on Pt particle in Pt/FSM-16 catalyst play an important role for the hydrodesulfurization ofthiophene. © 1997 Elsevier Science B.V.Keywords: Hydrodesulfurization; Mesoporous silicate; Pt/FSM-16 catalyst1. Introduction contained in vacuum gas oil and heavy oil. Therefore, the development of new catalysts based on large pore CoMo/AI203 catalysts have been widely used in the zeolites to treat large molecular organic sulfur com-hydrodesulfurization process of petroleum. However, pounds has been desired.recently, the development of highly active hydrode- Recently, mesoporous silicate materials such assulfurization catalysts, which are better than commer- MCM-41 [11] and FSM-16 (folded-sheet mesoporouscial CoMo/A1203 hydrodesulfurization catalysts, has material) [12,13] with large pore diameter have beenbeen claimed in the petroleum industry to produce developed. These new mesoporous silicate materialslower sulfur content fuels. Such metal-zeolite cata- are attracting wide attention as catalysts and catalystlysts have high possibilities as a new hydrodesulfur- supports.ization catalyst for petroleum [1-3]. We have In the present work, we examined the catalyticinvestigated the hydrodesulfurization of thiophene activities of various noble metals supported on meso-over transition metal Y zeolites (MeY) [4-7] and porous silicate FSM-16 for the hydrodesulfurizationnoble metals supported on USY and HZSM-5 zeolites of thiophene in order to develop highly active meso-[8-10]. These catalysts showed high catalytic activ- porous zeolite-based hydrodesulfurization catalysts.ities for the hydrodesulfurization of thiophene. How-ever, the pore diameter of these zeolites is too small fortreating large molecular organic sulfur compounds 2. Experimental *Corresponding author. Tel.: 81-143-47-3338; fax: 81-143-47- Hydrodesulfurization of thiophene over noble3129. metal/FSM-16 catalysts was carried out at 350°C0920-5861/97/$32.00 © 1997 Elsevier Science B.V. All rights reserved.PII S0920-5861 (97)00088-6
  2. 2. 62 M. Sugioka et al./ Catalysis Today 39 (1997) 61-67under 1 atm by using a conventional fixed bed flowreactor. Thiophene was introduced into the reactor by = . - - ~ PVFSM-16 •passing hydrogen through a thiophene trap cooled at0°C. The reaction products were analyzed by a gas- 2 ..................................._..~...~q._..~?./~chromatograph. l SO • Pd/FSM~I6 • FSM-16-supported noble metal catalysts were pre- 40pared by an impregnation method using noble metal 30 " - P~SH-16chloride aqueous solutions; the amount of metal load- 10 Ir/FSM-~ 6ing was 5 wt%. All catalysts were calcined at 500°C 0for 4 h in air and were reduced at 450°C for 1 h prior to 0 1 2 3 4 5 Time on stream[hr]the reaction. Presulfiding treatment of the catalysts W/F-37,90. hr/mol Hz/TIliophene=30was performed by 5% H2S-H2 mixture at 400°C for1 h. XRD analysis of the catalysts was carried out by Fig. 1. Hydrodesulfurization thiopheneover noble metal/FSM- ofusing Rigaku diffractometer with Cu K~t radiation. 16 catalystsat 350°C. We used mesoporous silicate FSM-16 (surface area970 m2/g, channel diameter 27 ,~) which was providedby Toyota Central R&D Labs., Japan. time and Pd/FSM-16 and Rh/FSM-16 catalysts showed lower steady state activity than CoMo/3. Results and discussion A1203 catalyst. Among noble metal/FSM-16 catalysts, Pt/FSM-16 showed the highest activity for the hydro-3.1. Catalytic activities o f noble metals supported desulfurization of thiophene and the activity of Pt/ on FSM-16 FSM-16 catalyst was higher than that of CoMo/A1203 catalyst. Pt/FSM-16 catalyst also showed higher activ- The catalytic activities of transition metals sup- ity than that of Pt supported on silica gel (SiO2) in theported on FSM-16 were examined at 350°C for the hydrodesulfurization of thiophene. The high andhydrodesulfurization of thiophene. It was found that stable activity of Pt/FSM-16 catalyst in the hydrode-the catalytic activities of transition metals/FSM-16 sulfurization of thiophene was kept even after it hadsuch as Ni/FSM-16, Co/FSM-16, Fe/FSM-16, W/ reacted for 20 h.FSM-16, Mo/FSM-16 (5wt% loading), 15wt% Table 1 summarizes the activities of various cata-MoO3/FSM-16, 5 wt% NiO-15 wt% MoO3/FSM-16 lysts used in this work.and 5 wt% COO-15 wt% MoO3/FSM-16 showed low As PffFSM-16 showed the highest catalytic activityactivity and their activity values were lower than that in the hydrodesulfurization of thiophene at 350°C, weof commercial CoMo/A1203 catalyst. Then we exam- studied in detail the catalyst performance and theined the catalytic activities of noble metals supported reaction mechanism in the hydrodesulfurization ofon FSM-16. Fig. 1 shows the hydrodesulfurization of thiophene over Pt/FSM-16 catalyst. It was found thatthiophene over various noble metal/FSM-16 catalysts the catalytic activity of Pt/FSM-16 was decreasedat 350°C. It was found that the catalytic activities of slightly by the presulfiding with H2S-H2 mixture asnoble metal/FSM-16 varied remarkably with the kind shown in Table 1. Thus, we used the Pt/FSM-16of noble metals. The order of the activities of these catalyst without presulfiding.catalysts for the hydrodesulfurization of thiophene In the hydrodesulfurization of thiophene over Pt/after 2 h reaction was as follows: Pt/FSM-16>Pd/ FSM-16 catalyst, main reaction products were C4FSM-16>Rh/FSM-16>>Ru/FSM-16, Ir/FSM-16, Au/ hydrocarbons (butane 88%, butenes 12%); traceFSM-16. amount of C1-C3 hydrocarbons was also formed. The initial activities of Pt/FSM-16, Pd/FSM-16 and These results indicate that Pt/FSM-16 catalyst hasRh/FSM-16 were higher than that of commercial high hydrogenating ability for unsaturated Ca hydro-CoMo/A1203 catalyst (dotted line). However, the carbons and low hydrocracking activity for hydrocar-activities of these catalysts decreased with the reaction bons in the presence of hydrogen sulfide.
  3. 3. M. Sugioka et al./Catalysis Today 39 (1997) 61~7 63Table 1 that of C o M o / A 1 2 0 3 catalyst for the reaction tempera-Catalytic activities of various metals supported on FSM-16 in the ture above 320°C. The low activity of Pt/FSM-16hydrodesulfurization of thiophene at 350°C (W/F-37.9 g h/mol,H2/Thiophene=30) catalyst below 320°C might be attributed to the sig- nificant resistance of reactant diffusion into the chan-Catalyst Conversion ( % ) a nel of FSM-16. That is to say, the comparable size of Reduced Sulfided Pt particles to the p o r e d i a m e t e r o f F S M - 1 6 w o u l d b e Catalystb Catalystc f o r m e d in the c h a n n e l o f F S M - 16 after the r e d u c t i o n o f5 wt% Ni/FSM-16 2 Trace P t / F S M - 1 6 b y h y d r o g e n [14] a n d Pt p a r t i c l e s f o r m e d5 wt% Co/FSM-16 2 9 i n h i b i t the d i f f u s i o n o f t h i o p h e n e into the c h a n n e l o f5 wt% Fe/FSM-16 Trace Trace F S M - 1 6 at the r e a c t i o n t e m p e r a t u r e b e l o w 320°C.5 wt% W/FSM-16 Trace 15 wt% Mo/FSM-16 15 1915 wt% MoO3/FSM-16 39 22 3.2. Improvement of catalytic activity of Pt/FSM-165 wt% NiO-15 wt% MoO3/FSM-16 22 355 wt% COO-15 wt% MoOa/FSM-16 30 32 Results showed that 5 wt% Pt/FSM-16 calcined at5 wt% Ru/FSM- 16 1 Trace 500°C had the highest catalytic activity for the hydro-5 wt% Au/FSM-16 1 Trace desulfurization of thiophene. However, it is uncertain5 wt% Ir/FSM-16 9 9 whether these preparation conditions are optimal or5 wt% Rh/FSM-16 32 31 not. Therefore, we examined the effect of preparation5 wt% Pd/FSM-16 56 625 wt% Pt/FSM-16 90 82 conditions on the catalytic activity of Pt/FSM-16 in order to obtain the optimal activity of Pt/FSM-165 wt% Pt/SiO2 (JRC-SIO-1) 51 -- catalyst for the hydrodesulfurization of thiophene.Commercial CoMo/A1203 -- 60 Fig. 3 shows the effect of Pt loading on the activityaReaction after 2 h. of Pt/FSM-16 catalyst. The catalytic activity increasedbCatalysts were reduced at 450°C for 1 h ° with the increase of Pt loadings up to about 3.5 wt%CCatalysts were sulfided at 400°C for 1 h after reduced at 450°C. and the activity became constant for loading above 3.5 wt%. Thus, it can be concluded that 5 wt% loading of Pt on Pt/FSM-16 is enough for obtaining the 100 maximum activity. ,o Pt/FSM-16 ~~ "~ 50 Go 80 70 / / l ~ l / f i •~ " """"~" coMo~ " " "~ 100 90 ~ 40 80 30 70 60 10 8 5o 0 , , i i i i 200 220 240 260 280 300 320 340 360 380 400 Reaction temperature[C] 3OFig. 2. Comparison of catalytic activity of Pt/FSM-16 with that of 20commercial CoMo/A1203 catalyst in the hydrodesulfurization of 10thiophene. 1 2 3 4 5 6 Fig. 2 shows the comparison of the activity of FSM- Pt loading[w1%]16 catalyst with CoMo/Al203 catalyst. It was found Fig. 3. Relationship between Pt loading and the catalytic activitythat the catalytic activity of Pt/FSM-16 is higher than of Pt/FSM-16 in the hydrodesulfurization of thiophene at 350°C.
  4. 4. 64 M. Sugioka et al./ Catalysis Today 39 (1997) 61-67 lOO lOO 90 80 80 70 70 Z 6o 9[ 6o i ii •~ 50 3O 20 I~-Ir Pt-Pd P~-Rh PI-Ru 25~1%PI,FSM-165wI%Pt/FSM-16 10 0 i , t i Fig. 5. Catalytic activity of Pt (2.5 wt%) combined with other 200 300 400 500 600 700 800 noble metals (2.5 wt%) supported on FSM-16 in the hydrodesul- Calcination temperature [C] furization at 350°C.Fig. 4. Effect of calcination temperature of Pt/FSM-16 on thecatalytic activity in the hydrodesulfurization of thiophene at 350°C. to learn more about the origin of high and stable activity of Pt/FSM-16 catalyst. The introduction of hydrogen sulfide (3 ml/min) was performed using a Fig. 4 shows the effect of calcination temperature microfeeder with a glass syringe; the concentration ofon the catalytic activity of Pt/FSM-16. The catalytic hydrogen sulfide in the hydrogen stream was ca.activity of Pt/FSM-16 increased slightly up to the 5 vol%. The catalytic activity of Pt/FSM-16 wascalcination temperature at 500°C and it decreased remarkably decreased by the introduction of hydrogenabove 500°C. It was found that the calcination of sulfide in the course of hydrodesulfurization reaction.the catalyst at 500°C is the optimal condition. However, the decreased activity was almost restored In the previous paper [10], we showed that the after cutting off the introduction of hydrogen sulfide assteady state activity of Pt/USY catalyst in the hydro- shown in Fig. 6. This shows that hydrogen sulfide isdesulfurization of thiophene was remarkably reversibly adsorbed on Pt/FSM-16.improved by the combination with other noble metals. Furthermore, the activity of Pt/FSM-16 catalystsCombination of Pt with Pd was the most effective. was slightly decreased after the presulfiding with 5%Thus, we tried to enhance the steady state activity of H2S-H2 mixture at 400°C as shown in Fig. 6. ThesePt/FSM-16 by combining Pt (2.5 wt%) with other results indicate that the Pt/FSM-16 catalyst has highnoble metals (2.5 wt%). It was found that the steadystate activity of Pt/FSM-16 was not improved by thecombination of Pt with other noble metals and theactivity of 2.5 wt% Pt/FSM-16 was decreased by the 1oo 90addition of 2.5 wt% other noble metals except Pd as 80shown in Fig. 5. 703.3. Properties of Pt/FSM-16 catalyst 5O agt,i ~ ) 4O Pt/FSM-16 catalyst showed high and stable activity 3Ofor the hydrodesulfurization of thiophene among the 2O 10noble metals supported on FSM-16. We also studied in 0more detail concerning the catalytic properties of Pt/ 2 3 6 Time on stream [hr]FSM-16 in the hydrodesulfurization of thiophene. The effect of introduction of hydrogen sulfide on the Fig. 6. Reversible inhibition of hydrogen sulfide in the hydro-catalytic activity of Pt/FSM-16 was examined in order desulfurization of thiophene at 350°C.
  5. 5. M. Sugioka et al./Catalysis Today39 (1997) 61-67 65sulfur tolerant properties for the hydrodesulfurizationof thiophene as well as Pt/HZSM-5 catalyst describedin the previous paper [9]. On the other hand, as mentioned in the previouspapers [7-9], the acid site, especially Br~nsted acidsite, of H-zeolites (HY, USY, HZSM-5) as support in 5wt~/FSM-16noble metal/H-zeolite catalysts plays an importantrole for the hydrodesulfurization of thiophene. In this 5wt~Pt/FSM-~6study, we examined the effect of introduction ofammonia on the catalytic activity of Pt/FSM-16 in FS~I 6the hydrodesulfurization of thiophene in order to ,0 20 30 ,0 5o ,; ,; 8; --clarify the role of acidic properties of Pt/FSM-16 in Ze/degreethe hydrodesulfurization of thiophene. The introduc- Fig. 8. XRD patterns for various noble metal/FSM-16 catalyststion of ammonia (3 ml/min) was carried out using before reduction.microfeeder with glass syringe as well as the intro-duction of hydrogen sulfide. It was revealed that thecatalytic activity of Pt/FSM-16 was decreased by the 3.4. XRD analysis of Pt/FSM-16 catalystintroduction of ammonia (ca. 5 vol%) in the course ofhydrodesulfurization reaction and decreased activity Fig. 8 shows the XRD patterns of FSM-16 andwas completely regenerated after cutting off the intro- noble metal/FSM-16 before reduction. Almost theduction of ammonia as shown in Fig. 7. The catalytic same XRD patterns as that of FSM-16 were obtainedactivity of PffFSM-16 was remarkably decreased by before and after loading of noble metals. This indi-the addition of small amount (1 wt%) of sodium using cates that the structure of FSM-16 was maintainedsodium hydroxide aqueous solution to Pt/FSM-16 after loading of noble metals on FSM-16. No peakscatalyst. Furthermore, FSM-16 also showed the cata- of Rh were observed on Rh/FSM-16 catalyst. Onlytic activities for the isomerization of 1-butene the other hand, broad and sharp peaks of Pd and Pt(25 °C) and cyclopropane (150°C) and the dehydration were observed in the XRD analysis of Pd/FSM-16of 2-propanol (250°C), which are typical acid-cata- and Pt/FSM-16 catalysts. The same XRD patternlyzed reactions. These results indicate that the acid of Pt/FSM-16 was observed for PtJFSM-16 aftersites exist on Pt/FSM-16 catalysts and the acid sites reduction at 450°C. These results infer that Rh isplay an important role for the hydrodesulfurization of loaded on FSM-16 with high dispersion but Pdthiophene over Pt/FSM-16 catalyst. and Pt are loaded on FSM-16 with relatively large particle size. The order of the dispersion of noble metals on FSM-16 is assumed to be Rh/FSM-16>Pd/ FSM-16>Pt/FSM-16. This order is reverse to that IO0 of the steady state activity of noble metal/FSM-16 90 catalysts in the hydrodesulfurization of thiophene. It is 80 interesting that the lower dispersion of noble metals 7O .~ 60 on FSM-16, especially Pt/FSM-16, showed higher Nm ~ 5O int~ i catalytic activity for the hydrodesulfurization of 40 thiophene. 30 20 3.5. Mechanism of hydrodesulfurization of 10 thiophene on Pt/FSM-16 catalyst 0 3 qqmeoll stream [hr] Pt/FSM-16 showed higher catalytic activity thanFig. 7. Effect of introduction of ammoniaon the catalytic activity commercial CoMo/A1203 catalyst in the hydro-of Pt/FSM-16 in the hydrodesulfurizatrionof thiophene at 350°C. desulfurization of thiophene. We also studied the
  6. 6. 66 M. Sugioka et al.ICatalysis Today 39 (1997) 61-67mechanism of hydrodesulfurization of thiophene H2over Pt/FSM-16 catalyst. As mentioned above, the HzS + C4 H y d r o c a r b o n ~ ~ /acid site of FSM-16 in Pt/FSM-16 catalyst playsan important role for the hydrodesulfurization ofthiophene. That is, it is assumed that the acid siteof FSM-16 in the Pt/FSM-16 catalyst acts as activesites for the activation of thiophene, whereas Pt IT Spilloverparticles on FSM-16 act as active sites for the activa-tion of hydrogen in the hydrodesulfurization ofthiophene. Furthermore, we supposed the existenceof spillover hydrogen in the hydrodesulfurization of Scheme 1. The possible mechanism of thiophenehydrodesulfur- ization over Pt/FSM-16catalyst.thiophene over Pt/FSM-16 catalyst. Hence, we tried toconfirm the existence of spillover hydrogen in thehydrodesulfurization of thiophene. The catalytic mesoporous zeolite-based hydrodesulfurization cata-activity of Pt/SiO2 (quartz) mixed mechanically lyst for petroleum feedstocks.with FSM-16 was examined. It was found that theactivity of mixed catalyst obtained experimentally washigher than that of the calculated one (A+B) as shown 4. Conclusionin Fig. 9. This suggests that there exists spillover hydrogen on It was found that the Pt/FSM-16 catalyst showedPt/FSM-16 in the hydrodesulfurization of thiophene. high and stable activity for the hydrodesulfurization ofTherefore, we propose a possible mechanism for the thiophene, Therefore, it is concluded that Pt/FSM-16hydrodesulfurization of thiophene over Pt/FSM-16 might be a promising new hydrodesulfurization cata-catalyst as shown in Scheme 1. In the proposed lyst for the petroleum feedstocks.mechanism, thiophene is activated on the acid siteof FSM-16 and hydrogen is activated on Pt to formspillover hydrogen. The spillover hydrogen formed on AcknowledgementsPt particle attacks the activated thiophene formed onthe acid site on FSM-16. This work was partly supported by a grant-in-aid On the basis of the proposed mechanism, it would from Ministry of Education, Science and Culture,be possible to develop much more highly active Japan (082322060, 09650854) and the Petroleum Energy Center of Japan. The authors thank Toyota Central R&D Labs., Japan, for kind provision of FSM- 16 and also thank Dr. Yoshiaki Fukushima and Mr. Shinji Inagaki of Toyota Central R&D Labs., Japan, 35 (A) {0.1g) + S ~ (B) (0.1g) for their valuable comments. 30 Z5 References 15 10 [1] S. Gobolos,M. Breysse,M. Cattenot,T. Decamp,M. Lacroix, S J.L. Portefaix,M.L. Vrinat, Stud. Surf. Sci. Catal. 50 (1989) FSM-16(A) (0.1g) 243. 0 [2] R. Cid, J.L.G. Fierro,A.L. Agudo, Zeolites 10 (1991)95. 20 40 60 80 100 120 Tm~onlueam[min] [3] M. Laniecki,W. Zmierczak,Zeolites 11 (1991)95. [4] M. Sugioka,J. Japan Petrol. Inst. 33 (1990)280.Fig. 9. Hydrodesulfurizationof thiophene over FSM-16 (A), Pt/ [5] M. Sugioka, Y. Takase, K. Takahashi, Proceedings ofquartz (B), and mechanicallymixed(FSM-16(A)+Pt/quartz(B)) at JECAT91, 1991,p. 224.350°C. [6] M. Sugioka,Zeoraito(Zeolite) 10 (1993) 121.
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