Light Olefin Synthesis from Syngas over SulfideâZeolite Composite

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Light olefins synthesis from syngas over Sulfide-Zeolite composite catalyst Haibo Zhou, Su Liu, Junjie Su, Chang Liu, Lin Zhang, Wenqian Jiao, and Yangdong Wang Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b00940 • Publication Date (Web): 26 Apr 2018 Downloaded from http://pubs.acs.org on April 26, 2018

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Industrial & Engineering Chemistry Research

Light olefins synthesis from syngas over Sulfide-Zeolite composite catalyst Haibo Zhou, Su Liu, Junjie Su, Chang Liu, Lin Zhang, Wenqian Jiao, Yangdong Wang*

State Key Laboratory of Green Chemical Engineering and Industrial Catalysis, SINOPEC Shanghai Research Institute of Petrochemical Technology, Shanghai 201208, China

* Corresponding author Phone: +86-021-68462947 E-mail: [email protected]

1

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Abstract The development of the global economy leads to a rising demand for light olefins, which are the basic chemical raw materials. Recently, a series of bi-functional catalysts consisting of metal oxide and zeolite have been reported to perform excellent light olefins selectivity from syngas and attract much attention. In this article, a new sulfide (MoS2) – zeolite (SAPO-34) composite catalyst was studied for syngas conversion to light olefins. It was found that, the side reaction of methanation and hydrogenation of olefins to paraffins was suppressed by the introduction of potassium. Characterization results showed that the introduction of potassium could enhance the formation of K–Mo–S structure, at which the alcohol precursor formed. The optimized bi-functional catalyst MoS2-0.6K+SAPO-34 performed 12.5% CO conversion and 61.2% C2-C4 olefins selectivity.

2


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1. Introduction Light olefins, mainly produced by steam cracking of naphtha, are key raw chemical feedstock. With the depletion of petroleum resources and the growing demand for light olefins, the synthesis of light olefins from syngas (H2 and CO), which can be obtained by the gasification of coal, natural gas, and biomass, has attracted much attention 1-3. So far, the conversion of syngas to light olefins has been successfully commercialized by the indirect process, which can be resolved into two consecutive steps of the syngas to methanol synthesis process and methanol to olefins (MTO) process 4. On the other hand, the progress in synthesizing light olefins directly from synthesis gas, which would be more economic for less cost in equipment and production separation, is slow. Fischer–Tropsch synthesis (FTS) was once considered as the only effective technology for the direct synthesis of light olefins from syngas 2, 5

. However, the selectivity for light hydrocarbons is usually limited due to the

Anderson-Schulz-Flory (ASF) distribution, and the maximum C2-C4 hydrocarbons (including paraffins and olefins) selectivity is 58% 1. Thus, the developing of new efficient catalyst system for directly synthesis of light olefins from syngas is urgently required 6. Recently, several bi-functional catalysts were researched for production of light olefins

7-9

from syngas. These bi-functional catalysts could be described as

Oxide-Zeolite system 7. In the Oxide-Zeolite system, the reaction pathway mainly includes two steps: 1) intermediates formation from CO initial activation over oxide component; 2) light olefins via the C-C coupling over zeolite component. Although intermediate is not clearly defined (CH3OH

8

and CH2CO 7), these two substances can be regarded as

complexes containing CH2* species and expressed as CH2*-H2O and CH2*-CO. In the past, the low-temperature methanol synthesis catalyst CuZnAl oxides were also combined with zeolites for light hydrocarbons production 10, 11. However, strong hydrogenation ability of CuZnAl oxides leads to (Eqs. 3 and 4) the hydrogenation of the CH2* reactive intermediate and the light olefins, and the formation of CH4 and C2-C4 paraffins

10

. While, the Oxide-Zeolite system containing high-temperature 3



Page 4 of 22

alcohol synthesis catalysts (such as ZnCrAlOx, ZnZrOx, and MnOx) displayed weaker hydrogenation ability, and exhibited high olefin/paraffin ratio 12. 2 CO

+ H2

→

CH2* + CO2

(1)

n CH2*

→

CnH2n

(2)

CH2* + H2

→

CH4

(3)

CnH2n + H2

→

CnH2n+2

(4)

Meanwhile, some composite catalysts could be applied in one-step converting CO into aromatics

13, 14

. CO2 could also be used as carbon source for production of

light olefins 15 and liquid fuel 16, 17. Compared to that of CuZnAl oxides catalysts, the appropriate reaction temperature of molybdenum sulfide based catalysts is much higher. Besides, it is notable that there are significant levels of sulfur-containing compounds in raw syngas yielded by coal gasification, thus desulfurization is needed before methanol synthesis and FTS. Molybdenum sulfide based catalysts are considered as promising catalysts due to their resistance to sulfur poisoning and high activity for CO activation 18. In the present work, to expand the application bi-functional catalysts, a Sulfide-Zeolite system is presented to substitute Oxide-Zeolite system. CO and H2 are activated over the molybdenum sulfide based catalyst, and the C-C coupling occurs on the SAPO-34 surface. In this work, the bi-functional catalyst MoS2-K+SAPO-34 is investigated for light olefins synthesis from syngas. The influence of K addition amount and reaction conditions on catalytic performance has been investigated.

2. Experimental 2.1. Catalysts preparation The unsupported MoS2-based catalysts were prepared by co-precipitation method 19

. Briefly, aqueous solutions of acetic acid (CH3COOH) and ammonium

tetrathiomolybdate ((NH4)2MoS4) were simultaneously added to a container under continuous stirring. Hydrogen ion reacted immediately with the thiomolybdate and a black suspension was formed. The precipitate was aged at 70 °C for 2 h, and then filtered. The filtered cake (precipitate) was repeatedly rinsed with ethanol. The solid 4


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was dried at 100 °C for 12 h, followed by mixing with K2CO3 to thermal decomposition at 500 °C under N2 for 2 hour to obtain unsupported MoS2 catalysts. The MoS2 catalysts promoted by potassium are denoted as MoS2-xK (x= 0, 0.2, 0.4, 0.6, 0.8, 1.0), where x is the molar ratio of K/Mo. The CoMoSy-0.6K was also prepared by the same co-precipitation method with a Co/Mo/K molar ratio of 1:1:0.6. Instead of CH3COOH, Co(CH3COO)2 was used as the precipitant. In the case of the CoMoS-0.6K/AC catalyst, a kind of activated carbon (AC) was used as the support. It was washed by nitric acid and distilled water. The AC support was first impregnated with Co(CH3COO)2 and after drying at 80 °C for 12 h, (NH4)2MoS4 and K2CO3 were sequentially impregnated in the above Co loaded catalyst and dried at 80 °C for 12 h. After that, the material was calcined at 500 °C for 4 hour under N2 atmosphere. LiFeMnRh/SiO2 was prepared using silica gel as a support. Added metal contents were 1.0% Li, 0.1% Fe, 1.25% Mn, and 1.0% Rh (all percentages by weight). The support was impregnated with the required quantities of LiNO3, Fe(NO3)3·9H2O, Mn(NO3)2·4H2O and RhCl3·xH2O, in aqueous solution, using co-impregnation method. Impregnated sample was first dried 100 °C for 6 h, and then calcined at 450 °C for 4 hour. The CuZnAl catalysts were prepared by co-precipitation

20

. Two aqueous

solutions, one containing the desired amount of Cu(NO3)2, Zn(NO3)2 and Al(NO3)3 (the molar ratio of Cu/Zn/Al was 4/4/2) as precursors and the other containing Na2CO3 as the precipitant, were added simultaneously under vigorous stirring at 70 °C. The pH was controlled at about 7 by adjusting the flow rates of the two solutions. The resulting precipitate was aged at 70 °C for 1 h. The precipitate was filtrated, washed with deionized water, dried at 120 °C overnight, and calcined at 350 °C for 4 h. SAPO-34 sample was synthesized hydrothermally. Silica gel, AlOOH, and phosphoric acid were used as the precursors of Si, Al and P, while tetraethyl ammonium hydroxide (TEAOH) was used as the template. Typically, the precursors 5



Page 6 of 22

were dispersed with a ratio of SiO2: Al2O3: P2O5: TEAOH: H2O = 0.6: 1: 1: 3: 80. The mixture was stirred for 1 h, and then, crystallization was carried out at static conditions at 200 °C for 2 days. The resulting crystals were washed with distilled water, and dried overnight at 100 °C. The SAPO-34 was obtained by calcination in air at 550 °C for 5 h. 2.2 Catalyst Test The catalytic test was carried out in a fixed-bed reactor with equipped with on-line gas chromatograph. For each experiment, 1.5 g sample with grain sizes of 20-40 mesh was charged into a quartz reactor. The catalysts containing sulfide were pretreated in N2 gas flow at 400 °C for 3 h before reaction, while the catalysts containing oxide were pretreated in H2 gas flow at 400 °C for 3 h. Then, the reactor was cooled down to 80 °C, a syngas composed of CO (45%), H2 (45%) and N2 (10%) was introduced into the reactor. N2 in the syngas was used as an internal standard for the calculation of CO conversion. The products were analyzed by gas chromatographs (Agilent-7890B) after the reaction for 24 h when a steady state activity appeared. H2, CO, CH4, and CO2 were monitored by TCD using helium as the carrier gas. The carbon-containing products (including hydrocarbons, alcohols, and other oxygenates) were monitored by FID using N2 as the carrier gas. Hayesep Q and 5Å molecular sieves packed columns were connected to TCD, while DB-WAXETR and HP-AL/S capillary columns were connected to FID. CO conversion and CO2 selectivity were determined using an internal standard method.

Conversion

Selectivity

CO

CO 2

=

COinlet − COoutlet *100% COinlet

=

CO 2outlet *100% COinlet − COoutlet

The selectivity of individual hydrocarbons was obtained according to:

Selectivity

CnHm

=

nCnHmoutlet n

∑1 nCnHmoutlet

*100%

2.3 Characterization 6


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The catalysts were characterized by XRD, SEM, and XPS. The powder XRD patterns were recorded at room temperature on a Bruker-AXS D8 Advance X-ray diffractometer using Cu–Ka radiation in 40 kV and 200 mA. FE-SEM (Field Emission Scanning Electron Microscopy) analysis was performed on a Hitachi S4800 electron microscope. XPS measurements were recorded on a Quantum 2000 Scanning ESCA Microprobe. The carbonaceous C 1s line (284.6 eV) was used as the reference to calibrate the binding energy (BE).

3. Results and Discussion To expand the application of bi-functional catalysts and search appropriate CO activation sites with strong CO conversion capacity and weak hydrogenation ability of olefins, the performance of several representative alcohol synthesis catalysts with and without SAPO-34 are investigated and compared. The SAPO-34 exhibits CHA structure with mesoporous (Figures S1 and S2). It was believed that the weaker acidity (Figure S3) could prevent the hydrogenation of olefins 8. CuZnAl oxides have been widely applied in the methanol synthesis for many years. Rh based catalysts also attract much attention as a promising ethanol synthesis catalyst 21, 22. Alkali-promoted molybdenum sulfide catalysts have been widely studied in the conversion of syngas to mixed alcohols reactions 23-25. The catalytic test results over LiFeMnRh/SiO2, CoMoS-0.6K, CoMoS-0.6K/AC, CuZnAl with and without SAPO-34 were shown in Table 1. LiFeMnRh/SiO2 was considered as an ethanol synthesis catalyst at low temperature 26, while it showed high CH4 (88.9%) selectivity at 400 °C, suggesting the hydrogenolysis of reactive intermediate by strong hydrogenation ability of LiFeMnRh/SiO2 at such high temperature.

After

adding

SAPO-34,

the

CH4

selectivity

of

LiFeMnRh/SiO2+SAPO-34 decreased to 74.0%, and the C2-C4 hydrocarbons selectivity increased to 24.1%. Over the CuZnAl+SAPO-34 bi-functional catalysts, the selectivity of CH4 decreased from 67.8% to 3.6%, and the C2-C4 hydrocarbons (92.4%) became to the mainly products. The CoMoS-0.6K+SAPO-34 and CoMoS-0.6K/AC+SAPO-34 bi-functional catalysts also showed similar tendency of 7



Page 8 of 22

shifting CH4 to C2-C4 hydrocarbons after adding SAPO-34. This phenomenon suggested that the C1 reactive intermediate would couple in presence of SAPO-34, while the C1 intermediate would be further hydrogenated in absence of SAPO-34. It was observed that the main products were C2-C4 paraffins, rather than the aim products

C2-C4

olefins

over

bi-functional

catalysts

(except

for

CoMoS-0.6K+SAPO-34). Besides, it was interesting to find that the C2-C4 olefin/paraffin ratio remained below the valve of 0.1 over LiFeMnRh/SiO2, CoMoS-0.6K/AC, and CuZnAl in presence/absence of SAPO-34. It seemed that, olefins formed over the SAPO-34 would be further hydrogenated to paraffins in presence of H2, when contacting the alcohol synthesis catalysts. CoMoS-0.6K catalyst with weaker hydrogenation ability might prevent the olefin intermediate products from further hydrogenation, so high C2-C4 olefins selectivity could be achieved over the Sulfide-Zeolite system. Further studies were performed in Table 2 to understand the catalytic functions of the Sulfide-Zeolite system. CO2 was formed with a selectivity of 44-50% over the Sulfide-Zeolite system, which is close to the CO2 selectivity of the oxide-zeolite system

7, 8

. Low CO conversion was observed over CoS+SAPO-34, indicating the

poor CO activation ability of pure CoS. Meanwhile, MoS2+SAPO-34 showed high CO conversion of 75.4% and CH4 selectivity of 70.4%, exhibiting its strong hydrogenation ability. In the alcohol synthesis reactions, K was a well known additive, which could inhibit paraffin formation by weakening hydrogenation ability of catalysts

24, 27

. The introducing of 60% K weakened the activity of MoS2 with CO

conversion decreasing sharply from 75.4% to 19.7%. The introducing of K also significantly changed the organic products distribution, in which CH4 selectivity decreased to 14.6%, and total C2-C4 hydrocarbons selectivity increased to 81.4%, exceeding the maximum predicted for C2−C4 hydrocarbons according to the ASF distribution in typical FTS. Besides, it was notable that with the introducing of potassium, the aim products C2-C4 olefin surpassed C2-C4 paraffin, and became the major products, with corresponding olefin/paraffin ratio increased to 2.62. Cobalt, an F-T element, was considered to be an effective promoter to enhance the chain 8


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propagation and alcohol formation

28

. CoMoS-0.6K exhibited 90.6% total C2-C4

hydrocarbons selectivity, suggesting its better chain propagation ability. But the introducing of Co also leaded to remarkably CO conversion decrease, from 19.7% to 9.4%. To further understand the influence of the amount of the introducing K, a series of MoS2-xK catalysts with mole percentages of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 K were prepared. XRD patterns of MoS2-xK catalysts were shown in Figure 1. Pure MoS2 retained broad diffraction peaks of crystalline hexagonal MoS2 at 2θ = 14.4 °, 33.3 °, 39.7 °, and 58.7 ° 19. With introducing potassium into the MoS2, the peaks ascribed to MoS2 weakened. K2CO3 phase could not be observed in XRD pattern of MoS2-0.2K, indicating that K2CO3 phase was either highly dispersed on the MoS2 surface or in the presence of an amorphous form. But the peaks of K2CO3 started to appear in the MoS2-0.4K catalyst. And new crystal phase diffraction peaks at 21.7 ° and 27.8 °, related to the structure of rhombohedral K–Mo–S 18, were detected in the MoS2-0.4K catalyst. With the increase of K content, the intensity of the K2CO3 and K–Mo–S signal increased as expected. The scanning electron microscopy analyses of the catalysts before and after potassium introduction were shown in Figure 2. The images illustrated that potassium was well spread across the MoS2 catalyst particle after mixing and thermal decomposition, although some K2CO3 enriched on the edge of catalysts. Figure 3 showed the Mo3d-XPS spectra of MoS2-xK catalysts with different K loadings. The binding energy for Mo3d3/2 and Mo3d5/2 were around 229.0 and 232.2 eV (B. E.), respectively, which could be assigned to MoS2. With the introduction of K, the Mo3d binding energy shifted toward higher values. Combined with the results of XRD, the formation of K–Mo–S structure could be proposed. Table 3 and Figure S4 compared the catalytic performance of the K modified MoS2+SAPO-34 bi-functional catalysts. MoS2+SAPO-34 provided 70.4% CH4 with a high CO conversion, but C2-C4 olefin was seldom formed. Modification of the MoS2 with K2CO3 yielded more than 80% C2-C4 hydrocarbons and reduced the methane 9



Page 10 of 22

selectivity. The average carbon chain length rose to more than 2.5 from 1.37. It is notable the C2-C4 olefin/paraffin ratio increased with the amount of K increased. When 60% K was added, the C2-C4 olefin/paraffin ratio over MoS2-0.6K+SAPO-34 could achieve 2.62. The C2-C4 olefin/paraffin ratio over MoS2-0.8K+SAPO-34 dropped slightly to 2.52. Our results suggested that the CO hydrogenation sites significantly affected the product distribution in the subsequent conversion of C1 intermediate. C1 intermediate would easily be reduced to CH4 over MoS2 29, which exhibited highest hydrogenation activity, rather than desorbed and migrated to the coupling active sites. K was found to be effective additive to weaken the hydrogenation ability of MoS2

18, 29

. With the

introduction of K, CO conversion and CH4 selectivity decreased, while more C1 intermediate was able to migrate to the coupling active sites, resulting the increase of the C2+ product selectivity. The hydrogenation of olefins to paraffins could lead to the consumption of olefins. By weakening the hydrogenation ability, the introduction of K could suppress the side reaction, and enhance the C2-C4 olefin/paraffin ratio. So, a balance of hydrogenation and coupling functions associated with K and MoS2 was required to produce an optimum yield of C2-C4 olefins and to minimize the paraffins formation. And, 60% K introduction could significantly enhance the production of light olefins from syngas. The effect of reaction temperature on light olefins synthesis was also studied in Table S1. At 340 °C, MoS2-0.6K+SAPO-34 performed 8.4% CO conversion, and 43.1% oxygenates selectivity in the organic products. In the syngas to olefins reaction, high temperature could accelerate the conversion of syngas and the formation of hydrocarbons. It’s believed that the reaction of oxygenates dehydration over zeolites, which is thermodynamically feasible at high temperature, could drive CO conversion and C2-C4 olefins formation 8. At 400 °C, the C2-C4 olefins selectivity of 58.9% reached the peak value. But high temperature also boosted the hydrogenation activity, C2-C4 olefin/paraffin ratio decreased gradually with the increasing of reaction temperature. So, 400 °C would be chosen as the feasible reaction temperature, agreeing with the thermodynamically calculations 8. 10


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The effect of velocity (GHSV) of reactants on light olefins synthesis was investigated in Table S2. With the increase of the reactant feed flow rate, CO conversion decreased from 39.1% to 13.2%. High velocity shortened the retention time of C1 intermediate on the active sites, so some intermediate regenerated before coupling to form long chain products, resulting the increase of CH4 and Oxygenates selectivity and the decrease of C5+ hydrocarbons selectivity. Besides, short retention time also suppressed the side reaction of hydrogenation of olefins to paraffins, as a result, the C2-C4 olefin/paraffin ratio increased. The catalytic performance of MoS2-0.6K+SAPO-34 at different pressure were summarized in Table S3. Higher pressure benefited CO conversion, which rose from 12.5% to 22.4%. Meanwhile, higher pressure restrained the selective formation of olefins. Selectivity varied in the range from 61.2% to 53.6% for C2-C4 olefins whereas 21.1% to 27.4% for C2-C4 paraffins because of the further hydrogenation at the higher pressure. C5+ hydrocarbons selectivity also increased as the pressure increased, suggesting that higher pressure facilitated the chain growth of the organic intermediate.

4. Conclusions C2-C4 olefins synthesis from syngas over the Sulfide-Zeolite composite catalyst has been investigated in this work. By the introduction of potassium, the hydrogenation ability of MoS2 catalyst was weakened, the side reaction of methanation and hydrogenation of olefins to paraffins was suppressed. The optimized bi-functional catalyst MoS2-0.6K+SAPO-34, which performed 12.5% CO conversion and 61.2% C2-C4 olefins selectivity, could significantly enhance the production of light olefins from syngas. Due to the resistance to sulfur poisoning and high olefin/paraffin ratio, the Sulfide-Zeolite composite catalyst showed potential application prospect in the light olefins synthesis.

Supporting Information XRD patterns, N2 adsorption–desorption isotherms curve, and NH3-TPD profiles of 11



Page 12 of 22

SAPO-34, carbon chain length distribution over MoS2-xK+SAPO-34 composite catalysts with different K loadings, the effect of reaction conditions on light olefins synthesis. Figures S1−S4 and Tables S1-S3

Notes The authors declare no competing financial interest.

Acknowledgements The authors are grateful to the support from the China Postdoctoral Science Foundation (2017M611644).

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syngas over alkali promoted cobalt-molybdenum sulfide. Appl. Catal., A 2009, 366, 29. Yin, H.; Ding, Y.; Luo, H.; Yan, L.; Wang, T.; Lin, L., The Performance of C2 Oxygenates Synthesis from Syngas over Rh-Mn-Li-Fe/SiO2 Catalysts with Various Rh Loadings. Energ. Fuel. 2003, 17, 1401. Xiao, H.; Li, D.; Li, W.; Sun, Y., Study of induction period over K2CO3/MoS2 catalyst for higher alcohols synthesis. Fuel Process. Technol. 2010, 91, 383. Li, Z.; Fu, Y.; Bao, J.; Jiang, M.; Hu, T.; Liu, T.; Xie, Y., Effect of cobalt promoter on Co-Mo-K/C catalysts used for mixed alcohol synthesis. Appl. Catal., A 2001, 220, 21. Park, K. T.; Kong, J., Chemistry and Physics of Alkali Metals on MoS2 Surfaces. Top. Catal. 2002, 18, 175.

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Figure captions. Figure 1. XRD patterns of MoS2-xK+SAPO-34 catalysts with different K loadings Figure 2. SEM–EDS elemental maps of MoS2 and MoS2-0.6K Figure 3. Mo3d-XPS spectra of MoS2-xK catalysts with different K loadings

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Figure 1. XRD patterns of MoS2-xK+SAPO-34 catalysts with different K loadings (●: MoS2, ▲: K2CO3, ■: K-Mo-S)

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Figure 2. SEM–EDS elemental maps of MoS2 and MoS2-0.6K Yellow = sulfur; Red = molybdenum; green = potassium

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Figure 3. Mo3d-XPS spectra of MoS2-xK catalysts with different K loadings

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Table 1. Catalytic test results over LiFeMnRh/SiO2, CoMoS-0.6K, CoMoS-0.6K/AC, CuZnAl with and without SAPO-34 a

Catalysts

CO conversion

CO2 selectivity

LiFeMnRh/SiO2

47.4

LiFeMnRh/SiO2 + SAPO-34 b

Organic product selectivity (CO2 free)

C2-C4 olefin/paraffin

CH4

C2-C4 olefins

C2-C4 paraffins

C5+ hydrocarbons

Oxygenates

47.4

88.9

0.6

9.6

0.2

0.7

0.06

21.7

47.6

74.0

1.4

22.7

0.3

1.6

0.06

CoMoS-0.6K

6.8

45.9

37.3

11.8

35.5

0.6

14.8

0.33

CoMoS-0.6K + SAPO-34 b

9.4

44.7

6.2

64.7

25.9

3.2

0

2.50

CoMoS-0.6K/AC

4.1

-

37.7

2.7

42.1

0.8

16.7

0.06

CoMoS-0.6K/AC + SAPO-34 b

3.4

-

8.6

5.5

75.8

3.6

6.5

0.07

CuZnAl

8.7

40.4

68.4

1.2

14.7

1.6

14.1

0.08

CuZnAl+ SAPO-34 b

37.9

47.4

3.6

1.6

90.8

4.0

0

0.02

a b

Reaction conditions: p = 4.0 MPa, GHSV = 4000 h−1, T = 400 °C, n(H2)/n(CO)= 1 Mass ratio of alcohol catalysts:SAPO-34 = 1:1

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Table 2. Catalytic test results over sulfide catalysts+SAPO-34 a

Catalysts

CO conversion

CO2 selectivity

CoS + SAPO-34

0.2

CoMoS+ SAPO-34

Organic product selectivity (CO2 free)


CH4

C2-C4 olefins

C2-C4 paraffins

C5+ hydrocarbons

Oxygenates

-

11.4

21.6

67

0

0

0.32

1.3

47.4

49.3

2.8

45.3

0

2.6

0.06

MoS2 + SAPO-34

75.4

49.0

70.4

-

29.5

0.1

0

0

MoS2-0.6K + SAPO-34

19.7

50.0

14.6

58.9

22.5

3.7

0.3

2.62

CoMoS-0.6K + SAPO-34

9.4

44.7

6.2

64.7

25.9

3.2

0

2.50

a

Reaction conditions: m(sulfide catalysts):m(SAPO-34)= 1:1, p = 4.0 MPa, GHSV = 4000 h−1, T = 400 °C, n(H2)/n(CO)= 1

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Table 3. Catalytic test results over MoS2-xK+SAPO-34 bi-functional catalysts with different K loadings a

Catalysts

CO conversion

Organic product selectivity (CO2 free) CH4

C2-C4 olefins

C2-C4 paraffins

C5+ hydrocarbons

Oxygenates


MoS + SAPO-34

75.4

70.4

-

29.5

0.1

0

0

MoS -0.2K+SAPO-34

39.0

18.9

35.2

40.2

4.9

0.8

0.88

MoS -0.4K+SAPO-34

25.9

13.7

48.3

33.3

4.3

0.4

1.45

MoS -0.6K+SAPO-34

19.7

14.6

58.9

22.5

3.7

0.3

2.62

MoS -0.8K+SAPO-34

16.9

16.1

56.8

22.5

4.0

0.6

2.52

MoS -1.0K+SAPO-34

15.9

12.3

51.2

30.9

5.4

0.2

1.66

2

2

2

2

2

2

a

Reaction conditions: m(MoS2-xK):m(SAPO-34)= 1:1, p = 4.0 MPa, GHSV = 4000 h−1, T = 400 °C , n(H2)/n(CO)= 1

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Table of Contents

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Light Olefin Synthesis from Syngas over SulfideâZeolite Composite

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