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AZ9RBAYCAN KIMYA JURNALI № 4 2015
UDK 547.426.1.661
STUDY OF REACTION OF GLYCEROL STEAM REFORMING TO HYDROGEN
OVER BINARY Ni-Zr-O CATALYSTS
F.Ch.Hasanova, V.L.Baghiyev
Azerbaijan State Oil Academy [email protected] Received 09.06.2015
Reaction of glycerol steam reforming to hydrogen studied over binary nickel-zirconium oxide catalysts. Shown that the major products of the reaction of steam reforming glycerol over nickel oxide are hydrogen, carbon monoxide, carbon dioxide and methane, while on zirconium oxide in significant quantities formed and acrolein. Found that temperature greatly affects to the distribution of obtained reaction products. Thus at low temperatures over studied binary catalysts are formed mainly various hydrocarbons and oxygen-containing compounds, whereas at high temperatures the reaction proceeds toward the formation of hydrogen. It found that binary nickel-zirconium oxide catalysts with high content of nickel or zirconium exhibit high activity in the reaction of hydrogen generation.
Keywords: hydrogen, steam reforming, glycerol, nickel oxide, binary catalysts.
Introduction
It is known that one of the promising methods of producing hydrogen is the reaction of steam reforming of glycerol [1-3]. The main advantage of this method is that as the feedstock used glycerol obtaining in large quantities as a byproduct of biodiesel production [4]. For carry out this reaction, it is using various catalyst systems based on nickel, zirconium, cobalt and others. [5-7]. This paper presents the results of study of the reaction of steam reforming of glycerol into hydrogen over the binary nickel-zirconium-oxide catalysts.
Experimental technique
Binary nickel-zirconium-oxide catalysts of various compositions were prepared by precipitation from aqueous solutions of nickel nitrate and zirconium. The obtained mixture were evaporated and dried at 100-1200C, then decomposed to complete release of nitrogen oxides at 2500C and calcined at 7000C for 10 hours. Thus, the nine catalysts were synthesized with atomic ratio of the elements from Ni:Zn=9:1 to Ni:Zn= 1:9. Activity of synthesized catalysts were studied in flow unit with a quartz reactor in the temperature range 300-700°C. The reactor was charged with five ml of the catalyst grained 1.02.0 mm and its activity was studied in the reaction of steam reforming of glycerol. Outputs of hydrogen, methane and CO were analyzed on
the gas chromatograph with a column length of 2 m filled with activated carbon. The yields of acrolein and other liquid products of conversion of glycerol was determined on the chromatograph with a flame ionization detector using 3 m column filled with specially treated sorbent polisorb-1.
Results and Discussion
For comparative assessment of activity of binary oxide catalysts in the reaction of steam reforming of glycerol, we studied the activity of the individual oxides, from which the binary catalysts synthesized. Table 1 shows the results of studying the activity of the nickel oxide in the reaction of steam conversion of glycerol to hydrogen. It is seen that the reaction conversion of glycerol begins at 3000C. At this temperature formed 1.6% hydrogen, 5.6% methane and other light hydrocarbons. With increasing of temperature, the yield of hydrogen increases and at 7000C attains 80.4%. As seen from Table 1 carbon monoxide yield symbatically changed with the output of hydrogen. Over nickel oxide yield of carbon monoxide reaches 18.3%. With increasing of the reaction temperature, yield of methane passes through a maximum (38.5%) at 4000C. As seen from the table the conversion of glycerol to acrolein over nickel oxide not occurs throughout the studied temperature range. Beginning from reaction temperature 4500C the conversion of glycerol is 100%.
Table 1. Steam reforming of glycerol to hydrogen over nickel oxide (NiO)_
Temperature Reaction product yields Conversion
H2 CO CH4 Acrolein The amount of other products
300 1.6 5.6 0 5.1 12.3
350 15.6 0 22.2 0 20.5 58.3
400 33.6 1.4 38.5 0 15.3 88.8
450 47.7 2.9 29.4 0 20 100
500 58.6 5 21.5 0 14.9 100
550 66.9 7.9 14.5 0 10.7 100
600 73.4 11.5 8.2 0 6.9 100
650 79.0 15.1 5.9 0 0 100
700 80.4 18.3 2.3 0 0 100
The results of studies of the reaction of glycerol reforming to hydrogen over zirconium oxide shown in Table 2. As can see the reaction of glycerol conversion begins at 3000C. At this temperature mostly formed acrolein and low molecular weight hydrocarbons. Further increasing of temperature also leads to the formation of hydrogen, carbon monoxide and methane.
Table 2. Steam reforming of glycerol to hydrogen over zirconium oxide (ZrO2)._
Temperature Reaction product yields Conversion
H2 CO CH4 Acrolein The amount of other products
300 0.2 1.6 6.5 8.3
350 3.6 0 3.9 13 20.5
400 7.5 0 4.5 6.2 11.8 30
450 11.8 2.9 9.1 12.9 8.3 45
500 18 7.9 9.1 18.1 9.4 62.5
550 23.8 20.2 3.7 19.7 20.7 87.5
600 31.1 24.5 0 15.1 26.8 97.5
650 40 28.8 7.3 23.9 100
700 48.3 33.1 0 18.6 100
As seen from Table 2 acrolein yield over zirconium oxide has a maximum (19.7%) at 5500C. Yield of methane also passes through a
maximum with increasing reaction temperature, but in this case, the maximum yield was 9.1%. From Table 2 it can be seen that maximum yields of hydrogen and carbon monoxide are observed at 7000C and are respectively 48.3 and 33.1%.
Fig. 1 shows the results of investigation of the reaction of steam reforming of glycerol into hydrogen over the catalyst Ni:Zr=1:9. As can see conversion of glycerol begins at 3000C. At this temperature formed 4.1% of acrolein and other organic compounds. Yield of acrolein with increasing of temperature increases up to 10% at 4000C and then decreases to zero at 5500C. Formation of carbon monoxide and methane beginning from 350 and 4500C respectively. In the studied range of temperature yield of carbon monoxide increases. while methane yield passes through a maximum at 5000C. The highest yields of carbon monoxide and methane are respectively 19.1 and 13.6%. The yield of hydrogen the main reaction product increases with temperature and reaches 82.8% at 7000C. Conversion of glycerol at temperatures above 6000C is 100%.
On the activity of binary nickel-zirconium-oxide catalysts affects their composition. Fig. 2 shows dependence of the activity of the nickel-zirconium-oxide catalysts in the steam reforming of glycerol into hydrogen from catalysts composition at temperature 6500C. It is seen that conversion of glycerol over all studied catalyst is equal up to 100%. With the increase of nickel content in the catalyst the hydrogen yield increases slightly to 85.4% for sample Ni:Zr = 3:7 and then sharply decreases to 41% over the sample Ni:Zr = 7:3 and then increased to 82% on a sample Ni:Zr = 9:1. A similar dependence was observed for the output of carbon monoxide, only its output does not exceed 25.4% at 6500C. The formation of methane as shown in Fig. 2 is observed only over catalyst Ni:Zr = 6:4.
Thus based on the obtained results can be said that the binary nickel-zirconium-oxide catalysts with high content of nickel or zirconium shows high activity in the reaction of formation of hydrogen.
48
F.Ch.HASANOVA, V.L.BAGHIYEV
Fig.1. Effect of temperature on the activity of the catalyst Ni:Zr = 1:9 in the reaction of steam reforming of glycerol into hydrogen: 1 - conversion, 2 - hydrogen, 3 - CO, 4 - CH4, 5 - acrolein.
Zr 9 8 7 6 5 4 3 2 1
Fig.2. Dependence of the activity of the nickel-zirconium catalysts in the steam reforming of glycerol into hydrogen from their composition: 1 - conversion, 2 - hydrogen, 3 - CO, 4 - CH4; T = 6500C.
References
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ИЗУЧЕНИЕ РЕАКЦИИ ПАРОВОЙ КОНВЕРСИИ ГЛИЦЕРИНА В ВОДОРОД НА БИНАРНЫХ
Ni-Zr-О-КАТАЛИЗАТОРАХ
Ф.Ч.Гасанова, В.Л.Багиев
Проведено изучение реакции паровой конверсии глицерина в водород на бинарных никель-цирконий-оксидных катализаторах. Показано, что основными продуктами реакции на оксиде никеля являются водород, монооксид углерода, углекислый газ и метан, в то время как на оксиде циркония в значительных количествах образуется также акролеин. Найдено, что температура реакции сильно влияет на распределение получаемых продуктов. Так, при низких температурах на изученных бинарных катализаторах образуются в основном различные углеводороды и кислородсодержащие соединения, тогда как при высоких температурах реакция идет в сторону образования водорода. Установлено, что бинарные никель-цирконий-оксидные катализаторы с большим содержанием циркония или никеля проявляют высокую активность в реакции образования водорода.
Ключевые слова: водород, паровая конверсия, глицерин, оксид никеля, бинарные катализаторы.
bínar Ni-Zr-O katalízatorlari üzorIndo qlíserínín hídrogeno buxar fazali
KONVERSÍYASININ ÓYRONiLMaSi F.^.Hasanova, V.L.Bagiyev
Binar nikel-sirkonium oksid katalizatorlan üzarinda qliserinin hidrogena buxar fazali konversiyasi óyranilib. Góstarilib ki, nikel oksidinda qliserinin buxar fazali konversiyasi reaksiyasinda asas mahsullar kimi alimr hidrogen. karbon qazi. karbon dioksid va metan. sirkonium oksidinda isa goxlu miqdarda akroleinda alinir. A§kar edilmi§dir ki, temperatur reaksiyanin mahsullarinin paylanmasina güclü tasir edir. Bela ki, a§agi temperaturda tadqiq olunan binar katalizatorlar üzarinda müxtalif karbohidrogenlar va oksigen tarkibli birla§malari amala galir yüksak temperaturda isa reaksiya hidrogenin amalagalmasi istiqamatina yónalir. Tayin olunub ki, nikel va ya sirkoniumla zangin olan binar nikel-sirkonium oksid katalizatorlari hidrogenin amalagalmasi reaksiyasinda yüksak sürati nümayi§ edir.
Agar sozlar: hidrogen, buxar konversiyasi, qliserin. nikel oksidi, binar katalizatorlari.
