- Email: [email protected]
An Economic Evaluation of the IFP Oxypyrolysis Process for Natural Gas Conversion to Gasoline Via Olefins
A. Holmen et al. (Editors), Natural Gas Conversion 1991 Elsevier Science Publishers B.V., Amsterdam
479
AN ECONOMIC EVALUATION OF THE IFP OXYPYROLYSIS PROCESS FOR NATURAL GAS CONVERSION TO GASOLINE VIA OLEFINS
C. RAIMBAULT" and C.J. CAMERON' Divisions of "1'Economie et de la Documentation and "Cinktique et Catalyse, Institut Ff.an(;ais du Pbtrole, 1 8.1 4 avenue de Bois-Prbau BP 311 92506 Rueil-Malmaison, fiance. ABSTRACT Economic evaluations of the IFP Natural Gas Oxypyrolysis Process for the conversion of natural gas to ethylene and to synthetic gasoline are presented. The evaluations are based on Norwegian natural gas compositions and on the assumption of a conventional low temperature separation train. Ethylene production cost is estimated to be of the order of 435 US$/ton (gas at $2/MMBTU) to 540 US$/ton (gas at $3/MMBTU) in an industrialized environment. The production cost of synthetic gasoline would be of the order of $0.90/gallon (gas at $0.50/MMBTU), under conditions similar to those for the MTG process. As the production cost is largely dependent on the cost of the separation technology (approximately 90 % of the total capital investment), new methods of separation should reduce the production costs by at least 20%. INTRODUCTION Detailed studies involving the Oxidative Coupling of Methane (OCM) reaction, with methane/oxygen mixtures, have produced the following conclusions: 1) methane conversion, oxygen conversion and Cz+ selectivity are simultaneously increased when both the linear space velocity and catalyst bed hot spot (hs) temperature are increased [1,2]; 2) the presence of Cz+ alkane components in the methane/oxygen charge leads to the preferential conversion of oxygen by the Cz+ alkanes (i.e. low methane conversion) and to substantially lower
Cz+ product selectivity [3-51; and 3) operating at higher hs temperatures and linear space velocities significantly increases the concentration of hydrogen in the product stream [3-51. The combination of these effects have led us to examine and to develop a new idea for the processing of natural gas. This new concept, referred to as 'oxypyrolysis', combines the oxidative coupling of methane, in the co-feed mode of operation, at high temperature and linear space velocity with the pyrolysis of the product Cz+ alkanes and the C2+ alkane components in natural gas. Two very important products, which have been largely ignored in OCM studies, are hydrogen and heat. The first product is extremely useful either as a means of recoveriiig
A Simplified Process Scheme for the Oxypyrolysis of Natural Gas to Gasoline via Ethylene
A
Natural + Gas
T
d
._
Fig 1.
h
L
H)
CH4 + H 2 0
I
Oligomerization
;:-$
CH4, H2, CO
C2+ alkanes
light alkanes
Gasoline and Diesel
Methanator Hydrogen Elimination
Dimerization
mw Y c4+
W P
0
48 I
potentially lost carbon in the form of methane or, eventually, for the synthesis of ammonia and urea [6,7]. The overall yield of non-selective oxidation products, CO and COZ, can be substantially reduced by combining the hydrogen efffuent stream with a CO and, if necessary, part of a COz stream. The resulting mixture is reacted to regenerate methane and produce water. This exothermic process step increases the overall carbon yield of the process at the expense of hydrogen. On the other hand if hydrogen were to be recovered, a relatively pure hydrogen stream could be combined with nitrogen, resulting from the air separation unit, to generate ammonia. The reaction of ammonia with COz to produce urea would both decrease potential carbon loss and produce a high valued and easily transportable commodity chemical. The latter idea, although interesting, involves a much higher capital investment. Operating the oxypyrolysis process at high catalyst bed hs temperature, that is at high initial effluent temperature, is particularly advantageous for two reasons. First, the rate of reactions are strongly influenced by the temperature. Selective oxidation appears to be more effected by temperature than non-selective oxidation, as the selectivity toward Cz+ products is found to increase with increasing temperature, provided t h a t t h e linear space velocity is substantially increased. Second, the required increase in linear space velocity has an important effect on reducing the size of any potential industrial reactor. These combined effects along with catalyst performance and the separation technology chosen for the targeted product(s) are important factors in the evaluation of any process. The data given in this work are refined estimates based on known catalytic performances and on well known cold-box separation technology. Although existing cold-box technology is undoubtedly not the most adapted for this process, it provides an excellent conservative estimate for total production cost of ethylene and gasoline, based on this process. More adapted separation methods should reduce the production cost by at least 20 %. PROCESS SCHEME
A simplified scheme for the IFP Natural Gas Oxypyrolysis (NGOP) Process to gasoline via olefins is shown in Figure 1. This process includes: 1) separation of methane from natural gas, 2) separation of oxygen from air, 3) oxidative coupling of methane (OCM) with oxygen, 4) injection of the Cz+ alkane stream into the OCM effluent, 5 ) pyrolysis of the combined OCM effluent/Cz+ alkane stream, 6) effluent separation, 7) olefin dimerization and oligomerization, and 8) carbon recovery by CO and COZ hydrogenation to methane. In order to obtain the most favorable heat balance, it is important to group all of the hot process sections together whenever possible. The process scheme, shown in Figure 1, has been devised in such a way as to keep a hot-cycle (composed of methanation, heat exchange, pre-heating, oxidation and pyrolysis) separate from the cold-cycle (separation). Typical results (steps 1 and 3-5 of the process) from a small fixed bed reactor indicate the type of effluent compositions which may be obtained with pure methane or with a simulated Norwegian natural gas containing 9 %vol Cz+ [4,5], Table 1. The fixed bed version of
482
TABLE 1
Product Flow Rates and Other Data for Oxypyrolysis Experiments [4,5]." Experiment Number Par m e t e r 1 2 3 Pyrolysis Temp. (OC) Rate In (mol/hr) CH4 C2HGb
4
850
850
850
880
2.500 0 0.248
2.500 0.250 0.248
2.500 0.250 0.375
2.500 0.250 0.248
0.318 0.303 0.001 0 2 0.001 0.043 0.018 co 0.103 0.059 co2 0.292 0.267 CZH4 0.104 0.094 C2H6 0.010 0.011 C3H6 0 C3H8 0 2.168 2.032 CH4 0.499 0.358 H20 13.3 18.7 CH4 Conv. (%) >99.6 >99.6 0 2 Conv. (%) 76.8 75.2 C2H6 Conv. (%) C2H4/C2H6 2.9 2.8 3.0 "The catalyst bed hot spot temperature was 88OoC. *Ethane added to the reactor after the catalyst bed.
0.366 0.001 0.011 0.059 0.294 0.046 0.016 0 2.202 0.365 11.9 >99.6 >98 6.4
0 2
Rate Out (mol/hr) H2
0.124 0.001 0.017 0.059 0.105 0.036 0.008 0 2.118 0.359 15.3 >99.6
483
O x i d a t i v e C o u p l i n g w i t h Oxygen
SENSITIVITY ANALYSIS : *
:
/
I I
I
0
10
20
30
40
CONVERSION
50
60
Fig. 2. Variation of the weight per cent gasoline yield as a function of methane conversion for the oxypyrolysis of Norwegian natural gas. The hatched box represents the region in which current catalysts (IFP) are known to be able to operate for over several hundred hours of continuous operation.
484
this process is generally preferred when oxygen concentrations are below about 11 vol% with respect to methane. Above this oxygen concentration, the fluidized bed version will probably be required due to the excessive adiabatic temperature rise (71. Preferred operating conditions for the IFP NGOP process are similar to those required for an ethane steam cracker (81, they are: temperature - 850-930"C1pressure - 1-3 bar relative, methane to steam ratio - 0-0.25 mol%. Operating above 930°C leads to a substantial increase in selectivity toward CO, due to the steam reforming of Cz+ products. Pressures as high as 3 bar have been shown to be acceptable for this process; however, beyond that pressure Cz+ selectivity is lowered and cannot be completely recovered by further increasing the linear space velocity [9]. Ethane steam cracking is generally effected in the 1-2 bar pressure region. Increased water vapor partial pressure in the reactor, although advantageous in terms of Cz+ selectivity, is costly due to the energy requirements for heating then cooling the added water. SENSITIVITY ANALYSIS Variation in gasoline yield, including kerosene and diesel fuel as gasoline equivalent, as a function of methane conversion for different values of overall process are shown in Figure 2. Natural gas consumption, for feedstock use and energetic requirements, has been taken into account in the analysis. The resulting curves are calculated based on several experimental results, and have been extrapolated to areas which are not necessarily experimentally attainable. These data should be examined from the perspective of the relative evolution of the yield as a function of process selectivity rather than from the view of the absolute value of the figures. The hatched area represents the currently attainable region using a fixed bed, IFP NGOP Process. PROCESS ECONOMICS The investments, included in Table 2, concern the implantation of an IFP NGOP unit in a remote area, using a 1.4 localization factor with respect to the US Gulf Coast. The production cost estimations for both fixed and fluidized bed versions of the IFP NGOP Process are very similar, contrary to the difference found for the Mobil MTG Process [lo], Figure 3. The latter process requires a higher investment than the IFP Process, as can be seen from the production cost for gas at 0 $/MMBTU (US$ per Million British Thermal Units). Although the total fixed capital is substantially higher, the IFP Process should have a significant advantage at natural gas prices below 1.5 $/MMBTU. The certain improvement in effluent separation could significantly lower production costs. The cost of ethylene production, not shown here, has been calculated using an industrialized zone localization factor of 1.0. It is estimated that the production cost of ethylene, using a similar process scheme, is of the order of 435 US$/ton (natural gas at 2 US$/MMBTU) to 540 US$/ton (natural gas at 3 US$/MMBTU).
485
TABLE 2 Product Cost of Gasoline from Natural Gas (Remote Area) MTG (Mobil)" NGOP (IFP)b Parameter fixed fluidized fixed fluidized Capacity (ton/year) Total Fixed Capital (Mill. US$)
295,000 317,000
610,000 645,000
688
614
909
994
Production Costs (Mill. US$/yr) Variable Costs -Natural Gas (0.5 $/MMBTU) -Others Labour (0.2 Mill. US$/shift) Fixed Costs -Depreciation (10 years) -Overheads
13.0 6.2 1.4
12.3 5.8 1.3
33.7 10.0 1.8
36.4 10.0 1.8
68.8 44.4
61.4 40.0
90.9 58.8
99.4 64.4
TOTAL
133.8
120.8
212.0
195.2
454 128
318 107
320 90
328 92
Overall Gasoline Production Cost (N.G. at 0.5 $/MMBTU) -US$ per ton -US cents per gallon
Values taken from reference [lo]. bKerosene and diesel fuel are produced and expressed as gasoline equivalents, on the basis of market prices.
486
P r o d u c t i o n C o s t s of Gasoline from N a t u r a l Gas
150
100
50 ........_............._._____
0
0
095
1
1,5
2
$/MMBTU Fig. 3. The production cost, in U.S. cents per gallon of gasoline, as a function of the cost of natural gas, in U.S. dollars per million British Thermal Units ($/MMBTU). Both fixed and fluidized bed options of the Natural Gas Oxypyrolysis Process (IFP) have similar production cost profiles. The fluidized bed version of the MTG Process (Mobil) is, however, substantially more favorable than the fixed bed version. Natural Gas Oxypyrolysis remains less expensive than MTG up to a natural gas price of 2 $/MMBTU.
481
CONCLUSION The IFP NGOP Process is a third option, along with the Mobil MTG and Shell SMDS processes, for natural gas upgrading to motor fuels. The great advantage of the IFP NGOP Process, compared to other known options, is the versatility of either producing ethylene, gasoline or diesel fuel with minor process modifications. The ratio of the latter two end products is determined by the catalyst and process conditions used in the dimerization/oligomerization steps of the process. The IFP NGOP Process is further characterized by the negligible sulfur content in the product [5], and the low COz emissions of the overall process. Advances in the IFP NGOP Process separation technology are the keys to the implantation of this process. Environmental and technico-economic pressures, for obtaining motor fuels from sources other than crude oil, will be the driving forces behind continued research in natural gas upgrading. ACKNOWLEDGEMENTS The authors wish to express their gratitude to S. Bonnaudet, J.-L. Dubois, A. Kooh, H. Mimoun, A. Pucci, D.V. Quang and A. Robine who have made important contributions toward the advancement of this project. REFERENCES A. Kooh, J.-L Dubois, H. Mimoun and C.J. Cameron, International Chemical Congress of Pacific Basin Societies, Preprint of 3B Symposium, Honolulu, 17-20 December 1989, paper 86, 60-61. 2 A. Kooh, J.-L Dubois, H. Mimoun and C.J. Cameron, Catal. Today, 6 (1990) 453-462. 3 C.J. Cameron, H. Mimoun, A. Robine, S. Bonnaudet, P. Chaumette and D.V. Quang, Fr. Pat. Appl. 88/04588, 1988. 4 H. Mimoun, A. Robine, S. Bonnaudet and C.J. Cameron, Chem. Lett., 12 (1989) 2185. 5 H. Mimoun, A. Robine, S. Bonnaudet and C.J. Cameron, Appl. Catal. 58 (1990) 269. 6 C. Cameron, Q. Dang Vu, J.-F. Le Page and H. Mimoun, Fr. Pat. Appl., 88/11312, 1988. 7 D.V. Quang and C.J. Cameron, see This Symposium. 8 A. Robine and C.J. Cameron, 199th A.C.S. National Meeting, 22-27 April 1990, Boston, U.S.A., to be published in L.F. Albright, B.L. Crynes, S. Nowak (Eds.), ‘Novel Methods of Producing Olefins and Aromatics’, Marcel Dekker Inc., New York, 1991. 9 M. Pinabiau-Carlier, A. Ben Hadid and C.J. Cameron, see This Symposium. 10 S.C. Nirula, Spring National AIChE Meeting, 2-6 April 1989, Houston, U.S.A. 1
479
AN ECONOMIC EVALUATION OF THE IFP OXYPYROLYSIS PROCESS FOR NATURAL GAS CONVERSION TO GASOLINE VIA OLEFINS
C. RAIMBAULT" and C.J. CAMERON' Divisions of "1'Economie et de la Documentation and "Cinktique et Catalyse, Institut Ff.an(;ais du Pbtrole, 1 8.1 4 avenue de Bois-Prbau BP 311 92506 Rueil-Malmaison, fiance. ABSTRACT Economic evaluations of the IFP Natural Gas Oxypyrolysis Process for the conversion of natural gas to ethylene and to synthetic gasoline are presented. The evaluations are based on Norwegian natural gas compositions and on the assumption of a conventional low temperature separation train. Ethylene production cost is estimated to be of the order of 435 US$/ton (gas at $2/MMBTU) to 540 US$/ton (gas at $3/MMBTU) in an industrialized environment. The production cost of synthetic gasoline would be of the order of $0.90/gallon (gas at $0.50/MMBTU), under conditions similar to those for the MTG process. As the production cost is largely dependent on the cost of the separation technology (approximately 90 % of the total capital investment), new methods of separation should reduce the production costs by at least 20%. INTRODUCTION Detailed studies involving the Oxidative Coupling of Methane (OCM) reaction, with methane/oxygen mixtures, have produced the following conclusions: 1) methane conversion, oxygen conversion and Cz+ selectivity are simultaneously increased when both the linear space velocity and catalyst bed hot spot (hs) temperature are increased [1,2]; 2) the presence of Cz+ alkane components in the methane/oxygen charge leads to the preferential conversion of oxygen by the Cz+ alkanes (i.e. low methane conversion) and to substantially lower
Cz+ product selectivity [3-51; and 3) operating at higher hs temperatures and linear space velocities significantly increases the concentration of hydrogen in the product stream [3-51. The combination of these effects have led us to examine and to develop a new idea for the processing of natural gas. This new concept, referred to as 'oxypyrolysis', combines the oxidative coupling of methane, in the co-feed mode of operation, at high temperature and linear space velocity with the pyrolysis of the product Cz+ alkanes and the C2+ alkane components in natural gas. Two very important products, which have been largely ignored in OCM studies, are hydrogen and heat. The first product is extremely useful either as a means of recoveriiig
A Simplified Process Scheme for the Oxypyrolysis of Natural Gas to Gasoline via Ethylene
A
Natural + Gas
T
d
._
Fig 1.
h
L
H)
CH4 + H 2 0
I
Oligomerization
;:-$
CH4, H2, CO
C2+ alkanes
light alkanes
Gasoline and Diesel
Methanator Hydrogen Elimination
Dimerization
mw Y c4+
W P
0
48 I
potentially lost carbon in the form of methane or, eventually, for the synthesis of ammonia and urea [6,7]. The overall yield of non-selective oxidation products, CO and COZ, can be substantially reduced by combining the hydrogen efffuent stream with a CO and, if necessary, part of a COz stream. The resulting mixture is reacted to regenerate methane and produce water. This exothermic process step increases the overall carbon yield of the process at the expense of hydrogen. On the other hand if hydrogen were to be recovered, a relatively pure hydrogen stream could be combined with nitrogen, resulting from the air separation unit, to generate ammonia. The reaction of ammonia with COz to produce urea would both decrease potential carbon loss and produce a high valued and easily transportable commodity chemical. The latter idea, although interesting, involves a much higher capital investment. Operating the oxypyrolysis process at high catalyst bed hs temperature, that is at high initial effluent temperature, is particularly advantageous for two reasons. First, the rate of reactions are strongly influenced by the temperature. Selective oxidation appears to be more effected by temperature than non-selective oxidation, as the selectivity toward Cz+ products is found to increase with increasing temperature, provided t h a t t h e linear space velocity is substantially increased. Second, the required increase in linear space velocity has an important effect on reducing the size of any potential industrial reactor. These combined effects along with catalyst performance and the separation technology chosen for the targeted product(s) are important factors in the evaluation of any process. The data given in this work are refined estimates based on known catalytic performances and on well known cold-box separation technology. Although existing cold-box technology is undoubtedly not the most adapted for this process, it provides an excellent conservative estimate for total production cost of ethylene and gasoline, based on this process. More adapted separation methods should reduce the production cost by at least 20 %. PROCESS SCHEME
A simplified scheme for the IFP Natural Gas Oxypyrolysis (NGOP) Process to gasoline via olefins is shown in Figure 1. This process includes: 1) separation of methane from natural gas, 2) separation of oxygen from air, 3) oxidative coupling of methane (OCM) with oxygen, 4) injection of the Cz+ alkane stream into the OCM effluent, 5 ) pyrolysis of the combined OCM effluent/Cz+ alkane stream, 6) effluent separation, 7) olefin dimerization and oligomerization, and 8) carbon recovery by CO and COZ hydrogenation to methane. In order to obtain the most favorable heat balance, it is important to group all of the hot process sections together whenever possible. The process scheme, shown in Figure 1, has been devised in such a way as to keep a hot-cycle (composed of methanation, heat exchange, pre-heating, oxidation and pyrolysis) separate from the cold-cycle (separation). Typical results (steps 1 and 3-5 of the process) from a small fixed bed reactor indicate the type of effluent compositions which may be obtained with pure methane or with a simulated Norwegian natural gas containing 9 %vol Cz+ [4,5], Table 1. The fixed bed version of
482
TABLE 1
Product Flow Rates and Other Data for Oxypyrolysis Experiments [4,5]." Experiment Number Par m e t e r 1 2 3 Pyrolysis Temp. (OC) Rate In (mol/hr) CH4 C2HGb
4
850
850
850
880
2.500 0 0.248
2.500 0.250 0.248
2.500 0.250 0.375
2.500 0.250 0.248
0.318 0.303 0.001 0 2 0.001 0.043 0.018 co 0.103 0.059 co2 0.292 0.267 CZH4 0.104 0.094 C2H6 0.010 0.011 C3H6 0 C3H8 0 2.168 2.032 CH4 0.499 0.358 H20 13.3 18.7 CH4 Conv. (%) >99.6 >99.6 0 2 Conv. (%) 76.8 75.2 C2H6 Conv. (%) C2H4/C2H6 2.9 2.8 3.0 "The catalyst bed hot spot temperature was 88OoC. *Ethane added to the reactor after the catalyst bed.
0.366 0.001 0.011 0.059 0.294 0.046 0.016 0 2.202 0.365 11.9 >99.6 >98 6.4
0 2
Rate Out (mol/hr) H2
0.124 0.001 0.017 0.059 0.105 0.036 0.008 0 2.118 0.359 15.3 >99.6
483
O x i d a t i v e C o u p l i n g w i t h Oxygen
SENSITIVITY ANALYSIS : *
:
/
I I
I
0
10
20
30
40
CONVERSION
50
60
Fig. 2. Variation of the weight per cent gasoline yield as a function of methane conversion for the oxypyrolysis of Norwegian natural gas. The hatched box represents the region in which current catalysts (IFP) are known to be able to operate for over several hundred hours of continuous operation.
484
this process is generally preferred when oxygen concentrations are below about 11 vol% with respect to methane. Above this oxygen concentration, the fluidized bed version will probably be required due to the excessive adiabatic temperature rise (71. Preferred operating conditions for the IFP NGOP process are similar to those required for an ethane steam cracker (81, they are: temperature - 850-930"C1pressure - 1-3 bar relative, methane to steam ratio - 0-0.25 mol%. Operating above 930°C leads to a substantial increase in selectivity toward CO, due to the steam reforming of Cz+ products. Pressures as high as 3 bar have been shown to be acceptable for this process; however, beyond that pressure Cz+ selectivity is lowered and cannot be completely recovered by further increasing the linear space velocity [9]. Ethane steam cracking is generally effected in the 1-2 bar pressure region. Increased water vapor partial pressure in the reactor, although advantageous in terms of Cz+ selectivity, is costly due to the energy requirements for heating then cooling the added water. SENSITIVITY ANALYSIS Variation in gasoline yield, including kerosene and diesel fuel as gasoline equivalent, as a function of methane conversion for different values of overall process are shown in Figure 2. Natural gas consumption, for feedstock use and energetic requirements, has been taken into account in the analysis. The resulting curves are calculated based on several experimental results, and have been extrapolated to areas which are not necessarily experimentally attainable. These data should be examined from the perspective of the relative evolution of the yield as a function of process selectivity rather than from the view of the absolute value of the figures. The hatched area represents the currently attainable region using a fixed bed, IFP NGOP Process. PROCESS ECONOMICS The investments, included in Table 2, concern the implantation of an IFP NGOP unit in a remote area, using a 1.4 localization factor with respect to the US Gulf Coast. The production cost estimations for both fixed and fluidized bed versions of the IFP NGOP Process are very similar, contrary to the difference found for the Mobil MTG Process [lo], Figure 3. The latter process requires a higher investment than the IFP Process, as can be seen from the production cost for gas at 0 $/MMBTU (US$ per Million British Thermal Units). Although the total fixed capital is substantially higher, the IFP Process should have a significant advantage at natural gas prices below 1.5 $/MMBTU. The certain improvement in effluent separation could significantly lower production costs. The cost of ethylene production, not shown here, has been calculated using an industrialized zone localization factor of 1.0. It is estimated that the production cost of ethylene, using a similar process scheme, is of the order of 435 US$/ton (natural gas at 2 US$/MMBTU) to 540 US$/ton (natural gas at 3 US$/MMBTU).
485
TABLE 2 Product Cost of Gasoline from Natural Gas (Remote Area) MTG (Mobil)" NGOP (IFP)b Parameter fixed fluidized fixed fluidized Capacity (ton/year) Total Fixed Capital (Mill. US$)
295,000 317,000
610,000 645,000
688
614
909
994
Production Costs (Mill. US$/yr) Variable Costs -Natural Gas (0.5 $/MMBTU) -Others Labour (0.2 Mill. US$/shift) Fixed Costs -Depreciation (10 years) -Overheads
13.0 6.2 1.4
12.3 5.8 1.3
33.7 10.0 1.8
36.4 10.0 1.8
68.8 44.4
61.4 40.0
90.9 58.8
99.4 64.4
TOTAL
133.8
120.8
212.0
195.2
454 128
318 107
320 90
328 92
Overall Gasoline Production Cost (N.G. at 0.5 $/MMBTU) -US$ per ton -US cents per gallon
Values taken from reference [lo]. bKerosene and diesel fuel are produced and expressed as gasoline equivalents, on the basis of market prices.
486
P r o d u c t i o n C o s t s of Gasoline from N a t u r a l Gas
150
100
50 ........_............._._____
0
0
095
1
1,5
2
$/MMBTU Fig. 3. The production cost, in U.S. cents per gallon of gasoline, as a function of the cost of natural gas, in U.S. dollars per million British Thermal Units ($/MMBTU). Both fixed and fluidized bed options of the Natural Gas Oxypyrolysis Process (IFP) have similar production cost profiles. The fluidized bed version of the MTG Process (Mobil) is, however, substantially more favorable than the fixed bed version. Natural Gas Oxypyrolysis remains less expensive than MTG up to a natural gas price of 2 $/MMBTU.
481
CONCLUSION The IFP NGOP Process is a third option, along with the Mobil MTG and Shell SMDS processes, for natural gas upgrading to motor fuels. The great advantage of the IFP NGOP Process, compared to other known options, is the versatility of either producing ethylene, gasoline or diesel fuel with minor process modifications. The ratio of the latter two end products is determined by the catalyst and process conditions used in the dimerization/oligomerization steps of the process. The IFP NGOP Process is further characterized by the negligible sulfur content in the product [5], and the low COz emissions of the overall process. Advances in the IFP NGOP Process separation technology are the keys to the implantation of this process. Environmental and technico-economic pressures, for obtaining motor fuels from sources other than crude oil, will be the driving forces behind continued research in natural gas upgrading. ACKNOWLEDGEMENTS The authors wish to express their gratitude to S. Bonnaudet, J.-L. Dubois, A. Kooh, H. Mimoun, A. Pucci, D.V. Quang and A. Robine who have made important contributions toward the advancement of this project. REFERENCES A. Kooh, J.-L Dubois, H. Mimoun and C.J. Cameron, International Chemical Congress of Pacific Basin Societies, Preprint of 3B Symposium, Honolulu, 17-20 December 1989, paper 86, 60-61. 2 A. Kooh, J.-L Dubois, H. Mimoun and C.J. Cameron, Catal. Today, 6 (1990) 453-462. 3 C.J. Cameron, H. Mimoun, A. Robine, S. Bonnaudet, P. Chaumette and D.V. Quang, Fr. Pat. Appl. 88/04588, 1988. 4 H. Mimoun, A. Robine, S. Bonnaudet and C.J. Cameron, Chem. Lett., 12 (1989) 2185. 5 H. Mimoun, A. Robine, S. Bonnaudet and C.J. Cameron, Appl. Catal. 58 (1990) 269. 6 C. Cameron, Q. Dang Vu, J.-F. Le Page and H. Mimoun, Fr. Pat. Appl., 88/11312, 1988. 7 D.V. Quang and C.J. Cameron, see This Symposium. 8 A. Robine and C.J. Cameron, 199th A.C.S. National Meeting, 22-27 April 1990, Boston, U.S.A., to be published in L.F. Albright, B.L. Crynes, S. Nowak (Eds.), ‘Novel Methods of Producing Olefins and Aromatics’, Marcel Dekker Inc., New York, 1991. 9 M. Pinabiau-Carlier, A. Ben Hadid and C.J. Cameron, see This Symposium. 10 S.C. Nirula, Spring National AIChE Meeting, 2-6 April 1989, Houston, U.S.A. 1