This paper presents the performance and characteristics of new-type sulfur tolerant shift catalyst QDB-04 and its industrial side-line test as well as the first-time industrial application in Lunan Chemical Fertilizer Plant of Shandong in China. The results show that the catalyst has high strength and strength stability, good low temperature activity and stability as well as low potassium bleeding ratio which well meet for the requirements of the methanol plant on catalyst performance in Lunan Chemical Fertilizer Plant.
Great attentions have been paid to the sulfur tolerant shift catalyst because of its excellent shift activity, sulfur tolerant ability and poisoning resistance. Many brands of such catalyst have been developed in the world, for example, K8-11 of BASF in Germany, SSK of TOPSOE in Denmark and QDB series of Qindao Lianxin Catalytic Materials Co., Ltd [
In order to solve the above problems, we adopted a new catalyst production method and developed a new- type sulfur tolerant shift catalyst QDB-04 with special inorganic and organic assistants, using a special method of potassium fixation. The catalyst was first applied in the new industrial methanol device of Shandong Lunan Second Nitrogen Fertilizer Plant of China in June 2004. In December 2005, the catalyst passed the industrial application appraisal organized by Shandong Science and Technology Committee. The catalyst has excellent strength, strength stability and activity stability, good low-temperature activity, strong resistance to low water/gas ratio and low sulfur as well as low alkaline metal bleeding ratio which well satisfy the demand of sulphur containing feed gas and medium pressure shift process conditions on catalyst performance and its comprehensive performance reaches first-rate level in China.
This paper presents the performance, characteristics and first-time industrial application of the new-type sulfur tolerant shift catalyst QDB-04 in Lunan Chemical Fertilizer Plant of Shandong in China.
Industrial catalysts of QDB-04 with special assistants were prepared by the dry-mixed method. The catalysts were extruded with special binder in order to get excellent strength performance.
The intrinsic activity of the catalyst was tested in a atmospheric micro reactor chromatography evaluation apparatus, using CO conversion ratio (XCO, %) as catalytic activity expression. The composition of the feed gas was 44% CO, 25% CO, 0.005% - 0.05% H2S and remaining for H2. The feed dry gas space velocity was 10,000 h−1, water-gas ratio was 1.0, weight of samples was 0.3 grams, particle size of catalyst was from 0.25 to 0.35 millimeter. The reaction temperature was selected for 260˚C, 350˚C, 400˚C.
The active component of cobalt and molybdenum was determined by spectrophotometric method, and the content of potassium assistant was tested by flame photometric detector.
The strength was tested in the DL-II intelligent strength test instrument with average size as the evaluation means. The strength stability and potassium bleeding ratio were checked by hydro-thermal treatment experiment in the original size pressure evaluation device, the strength and potassium content of samples were determined after treatment for ten hours in atmosphere of nitrogen and stream with a pressure of 50 bar, a temperature of 500˚C, a space velocity of 2000 h−1 and a water-gas ratio of 1.4.
The XRD characterization was performed on the Rigaku D/Max - 1200 X-ray diffractometer, using Cu-Ka1 target, graphite monochromator, 50 kv voltage in X-ray tube, 100 Ma current. The specific surface area, pore structure were determined by the PM-60 mercury intrusion porosimeter.
The experiment data are shown in
The ways of potassium assistant make a big influence on activity of sulfur tolerant shift catalysts [
Item | QDB-04 | Industrial catalyst A | ||
---|---|---|---|---|
Strength, N/cm | Retention ratio | Strength N/(particle) | Retention ratio | |
Fresh catalyst | 136.8 | / | 78.6 | / |
Catalyst after 1 year industrial used | 131.9 | 96.4% | 48.2 | 61.3% |
sulfur on the surface of the catalyst, lowers the sulfur loss rate of the catalyst when the H2S concentration is low in the feed gas [
After hydro thermal treatment, different samples show different potassium bleeding ration. By a special potassium fixation style, the potassium-bleeding ratio of the catalyst under the same appraisal conditions can be decreased greatly with a result of high activity stability. The experiments show in
On the whole low temperature shift industrial device of Shandong Lunan First Nitrogen Fertilizer Plant, 600 h and 1500 h industrial side-line test were carried out under the relative process conditions to the feed gas before and after deoxidation. The running data are shown in
It can be seen in
1) Whether with oxygen-containing or deoxidized feed gas, QDB-04 always showed high shift activity; under running conditions similar to those of Lunan First Nitrogen Fertilizer Plant, the outlet CO of QDB-04 was 1.93 - 3.91 (for deoxidized feed gas) and 1.98 - 4.54 (for oxygen-containing feed gas) which was the process index of CO < 8% of the plant at the same period of time and showed that the catalyst activity can completely satisfy the process condition requirements of the same kind of plants.
2) In the course of the test, several times of startups and shutdown occurred due to the valve failure and pipe corrosion, but the catalytic activity and bed resistance drop remained almost the same which showed that the catalyst has quite good activity and strength stability.
The domestically designed 100,000 t/a methanol device of Shandong Lunan Second Nitrogen Fertilizer Plant adjusts its shift furnace outlet CO index by adjusting the water/gas ratio. Its characteristics require the catalyst selected should have excellent ability to be tolerant of low water/gas ratio (0.3 - 0.4), relatively low activation temperature (240˚C) and good heat tolerance (heating point temperature 440˚C). For its first time operation, they chose our new-type sulfur tolerant shift catalyst QDB-04 (the diameter of the methanol shift furnace was 2.39 m,
H2S content in feed gas, % | 0.05 | 0.03 | 0.02 | 0.01 | 0.005 | |
---|---|---|---|---|---|---|
CO shift ratio % | Sample with special potassium fixation | 48.6 | 48.0 | 47.6 | 46.0 | 46.3 |
Sample with common potassium fixation | 48.2 | 41.2 | 37.8 | 35.2 | 32.4 |
Sample | Fresh catalyst K2O% | Hydrothermal treatment, K2O% | Potassium bleeding raito, % |
---|---|---|---|
Special potassium fixation style | 8.57 | 6.72 | 21.59 |
Common potassium fixation style | 8.58 | 3.26 | 62.00 |
Catalyst | CO shift ratio, % | |||
---|---|---|---|---|
265˚C | 350˚C | 400˚C | ||
H2S > 500 ppm | H2S > 500 ppm | H2S > 500 ppm | H2S, 160 ppm | |
Sample with special assistant | 7.10 | 38.64 | 59.68 | 56.13 |
Sample without special assistant | 6.32 | 33.38 | 54.51 | 48.98 |
Catalyst | H2S in the tail gas | |
---|---|---|
Penetration time, h | Balance time, h | |
Sample with special assistant | 4 | 12 |
Sample without special assistant | 10 | 27 |
Time | Space velocity, h−1 | Temperature, ˚C | Tail gas, CO% | Shift ratio, % | ||
---|---|---|---|---|---|---|
Top | Middle | Bottom | ||||
2010.06.01 | 2000 | 201 | 245 | 203 | 5.24 | 79.06 |
2010.06.05 | 2000 | 202 | 252 | 203 | 5.21 | 79.18 |
2010.06.09 | 2000 | 221 | 264 | 221 | 4.60 | 81.51 |
2010.06.13 | 2000 | 248 | 270 | 245 | 4.32 | 82.59 |
2010.06.17 | 2000 | 240 | 270 | 240 | 4.90 | 80.35 |
2010.06.23 | 2000 | 240 | 285 | 252 | 5.02 | 79.90 |
2010.07.03 | 2000 | 235 | 240 | 240 | 4.58 | 81.58 |
2010.07.07 | 2000 | 240 | 260 | 240 | 4.75 | 80.93 |
2010.07.12 | 2500 | 245 | 260 | 240 | 4.70 | 81.12 |
2010.07.17 | 3500 | 240 | 280 | 245 | 5.87 | 76.69 |
2010.07.20 | 2500 | 235 | 240 | 245 | 5.46 | 78.23 |
the reaction system totally had 6 thermocouples which respectively indicated the temperature of inlet, upper bed, lower bed and outlet. Catalyst was loaded in a 6.4m3 upper layer and a 6.6 m3 lower layer). Industrial operation started from June, 2012 and has applied from then on. At the start of the operation, because the new device was put into operation for the first time, the bed temperature had risen to a high 838˚C. But we tried our best to control the temperature and the device soon reached full-load operation.
Time | Space velocity, h−1 | Temperature, ˚C | Tail gas, CO% | Shift ratio, % | |||
---|---|---|---|---|---|---|---|
Inlet | Top | Middle | Bottom | ||||
2011.07.20 | 2500 | 216 | 298 | 278 | 245 | 2.97 | 87.87 |
2011.07.22 | 2500 | 217 | 304 | 293 | 263 | 3.06 | 87.51 |
2011.07.24 | 2500 | 224 | 318 | 300 | 269 | 3.83 | 84.49 |
2011.07.26 | 2500 | 225 | 318 | 296 | 273 | 3.38 | 86.25 |
2011.07.28 | 3000 | 223 | 324 | 332 | 301 | 4.05 | 83.63 |
2011.07.30 | 3000 | 223 | 344 | 346 | 323 | 4.01 | 83.79 |
2011.08.01 | 3000 | 224 | 307 | 352 | 336 | 6.81 | 73.19 |
2011.08.03 | 3000 | 224 | 304 | 349 | 332 | 5.91 | 76.53 |
2011.08.05 | 3000 | 225 | 306 | 355 | 338 | 5.33 | 78.72 |
2011.08.07 | 3000 | 221 | 309 | 359 | 338 | 5.15 | 79.40 |
2011.08.09 | 3000 | 222 | 318 | 362 | 341 | 4.47 | 82.01 |
Note: CO% in feed gas was 31.20%; Xco = (inlet CO%-outlet CO%)/[inlet CO% × (1 + outletr CO%)] × 100%.
Part of the industrial operation data of QDB-04 in Shandong Lunan Second Nitrogen Fertilizer Plant are shown in
1) At the beginning of the startup with low operation load, the 216˚C - 225˚C inlet temperature was enough to satisfy the requirements for CO outlet content (20% - 23%) in the methanol device which showed that the QDB-04 catalyst has good low temperature activity.
2) Due to the serious overheating of the QDB-04 catalyst at the beginning of the startup and several times of startups and shutdowns in the operation, the inlet temperature was improved about 10˚C (from 255˚C to 266˚C at full load) in the latter period of operation. In spite of this, the catalyst can still satisfy the requirements of the methanol device which shows the good activity and structure stability of QDB-04.
3) During the operation, the bed resistance drop maintained almost the same which showed that there’re no powdering and crushing of the catalyst in the course of operation and it keeps good strength and strength stability.
4) In the course of the new device running, there’re frequent startups and shutdowns and frequent changes of load, pressure, water/gas ratio, but QDB-04 catalyst still maintained stable performance and it showed resistance to operating condition fluctuations.
During the overhaul of Lunan Chemical Fertilizer Plant in March, 2012, part of the upper layer catalyst in the shift furnace was replaced because there was an overheating to 838˚C of the upper layer catalyst which might affect the long time production. After comparing the upper and lower layer samples, it was found that QDB-04 catalyst remained its whole particle with no caking and powdering, albeit the upper layer overheated sample got a paler color.
Comparison of the strength between the fresh sample and used sample is listed in
Contents of alkaline metal K2O and active component MoO3 are examined for the samples from upper and lower parts of the upper layer after one year industrial operation (see
Date | Gas flowrate | Temperature, ˚C | |||||||
---|---|---|---|---|---|---|---|---|---|
N m3/h | Inlet | First layer | Second layer | Outlet | Outlet | Resistance drop | |||
2012.06.04 | 5251 | 216 | 399 | 401 | 438 | 429 | 432 | 23.21 | 6 |
2012.06.10 | 8303 | 225 | 414 | 418 | 428 | 422 | 424 | 23.17 | 8 |
2012.06.25 | 10764 | 221 | 405 | 412 | 418 | 415 | 408 | 18.64 | 10 |
2012.07.15 | 12900 | 218 | 399 | 408 | 413 | 414 | 419 | 21.95 | 12 |
2012.08.01 | 27871 | 242 | 325 | 398 | 432 | 424 | 430 | 21.38 | 30 |
2012.09.25 | 30814 | 255 | 329 | 395 | 425 | 413 | 421 | 20.31 | 30 |
2012.10.10 | 32025 | 254 | 335 | 402 | 428 | 420 | 420 | 22.8 | 30 |
2012.10.25 | 27885 | 252 | 326 | 393 | 430 | 417 | 427 | 20.9 | 30 |
2012.11.30 | 24123 | 244 | 404 | 436 | 440 | 439 | 436 | 22.53 | 23 |
2012.12.16 | 33977 | 246 | 318 | 380 | 427 | 404 | 424 | 21.67 | 30 |
2013.01.07 | 33100 | 259 | 351 | 414 | 435 | 426 | 430 | 21.45 | 30 |
2013.01.21 | 33490 | 266 | 339 | 403 | 432 | 418 | 428 | 22.74 | 30 |
2013.02.27 | 33753 | 264 | 357 | 418 | 433 | 440 | 436 | 22.35 | 31 |
2013.03.31 | 28962 | 230 | 348 | 417 | 428 | 428 | 427 | 20.2 | 30 |
2013.04.21 | 33285 | 234 | 351 | 410 | 419 | 419 | 418 | 19.74 | 30 |
2013.05.15 | 33860 | 236 | 349 | 415 | 424 | 425 | 424 | 21.32 | 31 |
Catalyst | Strength, N/cm | Retention ratio, % | |
---|---|---|---|
Fresh sample | 137.8 | / | |
After one | Upper part of the upper layer | 135.4 | 98.3 |
Year’s operation | Lower part of the upper layer | 118.4 | 85.9 |
Middle part of the lower layer | 136.9 | 99.3 |
Catalyst | MoO3 content, | K2O, % | |
---|---|---|---|
Fresh sample | 7.49 | 8.23 | |
After one | Upper part of the upper layer | 7.36 | 8.24 |
Year’s operation | Lower part of the upper layer | 6.76 | 8.18 |
content remains the same to that of the fresh sample after one year’s operation, so are the MoO3 and K2O content from the upper layer, but the sample from overheated part shows paler color, and its MoO3 content is 6.76% which is obviously lower than that of the upper layer sample because of the sublimation of the active component during the period of overheating at over 800˚C [
Item | Fresh sample | After one year industrial operation | ||
---|---|---|---|---|
Upper part of upper layer lower layer | Lower part of upper layer | Middle part of | ||
Specific area | 115.1 | 105.2 | 92.7 | 99.4 |
Pore volume | 0.3609 | 0.2832 | 0.2953 | 0.3283 |
Average pore radius, nm | 62.81 | 59.50 | 63.63 | 59.99 |
Most probable radius, nm | 3.16 | 2.756 | 3.035 | 2.941 |
Pore distribution | ||||
<25 nm | 57.47 | 57.79 | 57.31 | 56.48 |
25 - 50 nm | 5.11 | 6.05 | 7.28 | 5.91 |
50 - 150 nm | 13.95 | 20.38 | 22.61 | 27.11 |
>150 nm | 23.39 | 15.79 | 12.79 | 10.51 |
XRD phase composition | γ-Al2O3 | γ-Al2O3 | γ-Al2O3 | γ-Al2O3 |
MgAl2O4 | MgAl2O4 | MgAl2O4 | MgAl2O4 | |
K2SO4 (micro amount) |
layer, among which small pores (<25 nm) remain almost the same but 50 - 150 nm medium-size pores are increased and big pores (>150 nm) are reduced obviously. The specific surface and pore structure changes are all caused by the serious overheating at the beginning of the startup.
It is also seen from
1) Experiment tests show that QDB-04 is a sulfur tolerant CO shift catalyst with special support and new-type assistant which have the properties of high strength and strength stability, high resistance to powdering, good low-temperature activity and activity stability, low alkaline metal bleeding ratio and easy sulfurization.
2) Industrial application results show that QDB-04 catalyst has low activation temperature, high low-temper- ature activity, high activity stability and high resistance to low water/gas ratio, which can perfectly satisfy the requirements of the methanol device of Lunan Nitrogen Fertilizer Plant. It overcomes the shortcomings (such as peeling and powdering that cause the rise of bed resistance) of the γ-Al2O3-based industrial catalyst.
3) Analysis of the unloaded sample shows that QDB-04 catalyst stands the one-year industrial operation and serious over-heating accident and retains the original bed resistance and catalysis activity. The unloaded samples keep high retention ratios of strength, pore structure and active component which show its good strength, strength stability and corrosion resistance. It can satisfy the requirements of methanol process conditions to catalyst activity, strength and structure stability.
BonanLiu,TiancunXiao,Peter P.Edwards,JiefeiXiao,GaoHui,QiuyunZong, (2016) Performance and Industrial Application of New-Type Sulfur Tolerant CO Shift Catalyst QDB-04. Open Journal of Inorganic Chemistry,06,15-22. doi: 10.4236/ojic.2016.61002