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Catalytic Hydrogenation of Carbon Monoxide and Dioxide Over Steel

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Catalytic Hydrogenation of Carbon Monoxide and Dioxide Over Steel Catalytic Hydrogenation of Carbon Monoxide and Dioxide over Steel BUFORD D. SMITH and ROBERT R. WHITE University of Michigan, Ann Arbor, Michigan The hydrogenation of carbon monoxide and carbon dioxide on various steel catalysts was studied in the temperature range of 800" to 1,300'F. and at pressures from 5 to 30 atm. The feed gases (3.75 to 20 SCFH) were passed over a catalyst bed of 1/8-h. steel balls supported in a brass-lined reactor 0.81 in. in dim. The percentage of carbon oxides in the feed was 30% in the runs using a Hz-COZ feed and varied from 15 to 38% in the runs with a H,-CO feed. The effects of temperature, pressure, feed composition, space velocity, and mass velocity were studied. Carbon deposition did not affect the activity of the catalyst and could be removed readily. The catalytic hydrogenation of carbon monoxide and carbon dioxide has re- ceived intensive study since the turn of TABLE1. STEEL CATALYSTCOMPOSITIONS (WEIGHT %) the century. In 1897 and 1902 Sabatier and Senderens (15, 16) reported their S. A. E. number original work on the synthesis of methane Constituent C1013 440 302 from hydrogen-carbon monoxide and Carbon 0.13-0.18 0.86-0.94 0.08-0.20 hydrogen-carbon dioxide mixtures in the Chromium - 16.5-18.0 17.0-19.0 presence of both reduced nickel and Manganese 0.50-0.80 0.30-0.60 2.0 reduced cobalt catalysts. In 1923 Fisher Silicon - 0.60 max. 1.0 max. and Tropsch (8) disclosed that iron was Sulfur 0.05 max. 0.30 max. 0.03 max. also an effective catalyst. Storch et al. Phosphorus 0.04 max. 0.30 max. 0.04 max. (18) summarized these early discoveries Molybdenum 0.40-0.60 and the investigations that followed. Nickel - 8.0-10.0 Buford D. Smith is with Humble Refining Com- pany, Baytown, Texas. TO SATURATOR I "2 BARTON 181 INDICATOR f 1BYPASSVALVET REACTOR ORIFICE -G9 WWC GO VALVE SUPPLY SAMPLIN SYSTEM n w HOKE NEEDLE VALVE LIQUID 44-s(TYPE) GROVE PRESSURE REGULATOR MOORE 65-D FLOW CONTROLLER SATURATOR WET TEST VENT FRoMkMETER Fig. 1. Flow diagrams for the experimental unit. Page 46 A.1.Ch.E. Journal March, 1956 A number of investigations have been directed toward the production of nieth- ane from carbon monoxide, carbon dioxide, and hydrogen. The results of a tHERMOC6UPLE WELL OPENING British project to upgrade town gas by CONE FITTINGS synthesizing methane from coal gas have been periodically reported (11, 6, 12). Commercial processes have heen outlined THERMO L PIPE in the literature (10, 5, a). Intensive kinetic studies of the synthesis of HEAT RESERV~IR methane on nickel catalysts from hydro- (V8" z1 I /4" STEEL BALLS) gen-carbon monoxide (1, 14) and hydro- I gen-carbon dioxide (4, 7) have been 16 GUAGE NlCHROME HEATING WIRE made recently. IlOV Recently (9) stainless steel pipe was 1 reported to be an effective methanization catalyst in the temperature range of HEATERS El ASED IN 950" to 1,500"F. The use of finely divided ALUNDUM C r(ENT stainless steel particles at lower tempera- tures to synthesize gasoline has been L disclosed (13). The high catalytic activity per unit of surface area shown by steel at 950" to 1,500"F.suggests that the greater surface area of a porous catalyst might be 22ov IIOVT ERMlCULlTE sacrificed to obtain the greater mechanical strength of nonporous-steel catalyst par- ticles. Catalyst crumbling and sintering 1 would be eliminated, making possible more severe operating and carbon- removal conditions. This work is a study ,GALVANIZED STEEL PLATE BOX (I8"x IB"x40") FILLED of the hydrogenation reactions on such WITH VERMICULITE a catalyst in the form of %-in. steel spheres. 110i v EXPERIMENTAL EQUIPMENT I A flow diagram of the experimental unit appears in Figure 1. Commercial gas cylin- ders (size 1A) were used as the feed-gas source with activated charcoal being used to remove the sulfur from the carbon monox- ide. The two feed streams were metered and controlled separately. The feed streams were mixed before leav- ing the control system. A wet test meter furnished accurate measurements of the feed and product rates, and the sampling system provided samples of the feed and product streams for Orsat and infrared analyses. The reactor (Figure 2) consisted of an electrically heated, insulated stainless steel pipe. Steel balls around the reactor pipe provided a large sensible heat reservoir and facilitated the maintenance of a constant reactor temperature. Thermocouple wells Fig. 2. Cross-sectional drawing of the reactor and cooler. provided entry for two iron-constantan couples into the mass of steel balls. A brass liner (not shown) extended the full length of the reactor tube to mask the catalytic steel surface. The copper&overed steel thermo- couple well shown in Figure 3 passed through the top pressure cone fitting and TABLE2 CATALYSTCOMPARISON RUNS supported the catalyst support at a point (Typical Portion of Data) about 6 in. below the middle of the insulated section of the reactor. A Brown potentiom- Cata- Tem- Press- Feed Space Feed composition, eter measured the bed temperature as indi- lyst perature ure, ratio velocity, volume '% cated by an iron-constantan couple placed Run age, OF. atm. HZ/CO mole/(hr.) CO COZ Hz within this well. hr. (sq. ft.) Catalyst: (21013, unpolished and untreated, 194 balls (0.0661 sq. ft. of surface) MATERIALS D33 2.7 1053 30 2.3 0.20 30.6 0.2 69.2 Aluminum tubing, steel Ermeto fittings, D34 3.8 1048 30 2.3 0.20 30.6 0.2 69.2 and Hoke needle valves with steel bodies D35 4.4 1051 30 2.3 0.20 30.6 0.2 69.2 were used in the experimental apparzitus. D36 5.2 1050 30 2.3 0.20 30.6 0.2 69.2 The feed gases were obtained commer- Vol. 2, No. 1. A.1.Ch.E. Journal Page 47 cially. According to the supplier's analyses The methane and helium had purities of for the carbon dioxide analyses. Carbon the hydrogen (electrolytic) had a purity of 99 and 99.99% respectively. monoxide, methane, and ethane concentra- 99.9% with less than 0.1% oxygen; the Three S. A. E. steel alloys (C1013, 440, tions in the gas samples were determined carbon monoxide was 96.8Oj, pure with 1% and 302) were used as catalysts in the form with a Baird model B recording infrared nitrogen, 0.36% carbon dioxide, 0.97% hy- of %-in. balls. Their chemical compositions spectrophotometer. The hydrogen in the gas drogen, 0.8% hydrocarbons, and 0.3202 are listed in Table 1. streams was determined by subtracting the mg./liter of sulfur; and the carbon dioxide volume of the other gaseous constituents contained only 0.5% air as an impurity. ANALYTICAL METHODS from the total gas volume. All analyses A conventional Orsat apparatus using a were on a water-free basis. The water pro- r--m 33% sodium hydroxide solution was used duced in a run was calculated by making 30 f -1 y 25 I 0 5 10 15 20 25 30 CATALYST AGE fHRSI Fig. 4. Effect of carburization on the percentage of contraction and methane produced by the unpolished c1013 steel balls. 0 5 10 15 20 25 30 CAlilLYST AGE IHRSI Fig. 3. Thermocouple well and catalyst Fig.- 5. Effect of nitriding- on the percentage of contraction obtained with the unpolished support. - C1013 steel balls. TABLE3. EVALUATIONOF THE UNTREATEDC1013 STEELCATALYST (Typical Portion of Data) Space velocity, Gas flow rates, Catalyst Temper- Pressure, Feed ratio moles/ Feed composition, volume '% std. cu. ft./hr. Run age, hr. ature, OF. atm. H2/CO H%/COt (hr.)(sq.ft.) CO COZ H2 CHI Feed Product Catalyst bed: 194 steel balls (0.0661 sq. ft. of surface) T2 2.3 847 30 - 2.3 0.20 - 30.4 69.6 - 5.02 5.00 T3 4.7 949 30 - 2.3 0.20 - 30.7 69.3 - 4.97 4.89 Catalyst bed: 194 steel balls (0.0661 sq. ft. of surface) PI 3.5 1,070 30 2.4 - 0.20 29.0 0.2 70.0 - 5.00 2.76 P4 5.1 1,070 20 2.4 - 0.20 29.0 0.2 70.0 - 5.00 2.87 Catalyst bed: 194 steel balls (0.0661 sq. ft. of surface) F1 2.7 1,069 30 5.5 - 0.20 15.4 0.2 84.1 - 5.05 4.36 F4 5.2 1,070 30 4.3 - 0.20 18.9 0.2 80.5 - 5.05 3.64 Catalyst bed: 388 steel balls (0.1322 sq. ft. of surface) A9 3.5 1,060 30 2.5 - 0.10 28.6 0.2 70.5 - 5.02 2.71 A12 6.4 1,062 30 2.4 - 0.13 29.1 0.2 69.9 - 6.63 3.65 Page 48 A.1.Ch.E. Journal March, 1956 both an oxygen and a hydrogen balance and averaging the two results. EXPERIMENTAL METHOD The first part of the experimental work TEMPERATURE: 1050'~ was concerned with the selection of the best PRESSURE: 30 ATMOSPHERES FEEO RATE: 5SCFH combination of steel composition and cata- FEED COMPOSITI0N:X)XH SOXCO lyst pretreatment. These pretreatments con- SPACE VELOClTY:O.PO MOL%;HR-FT? sisted of nitriding, carburizing, and defor- mation of the steel catalyst surfaces. I I The nitriding was accomplished in a small tubular furnace at 1,000"F.
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