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84
Chemistry Letters 2002
Production of Hydrogen Peroxide from Carbon Monoxide, Water, and Oxygen over Alumina
Supported Amorphous Ni Catalysts
ꢀ
Zhonglong Ma, Rongli Jia, Changjun Liu, and Zhentao Mi
State Key Laboratory of C1 Chemistry and Technology, School of Chemical Engineering and Technologies,
Tianjin University, Tianjin 300072, P. R. China
(Received May 27, 2002; CL-020456)
A novel amorphous Ni catalyst supported on alumina has
The supported catalysts were prepared as follows: the alumina
carriers were first impregnated with an aqueous solution of nickel
nitrate (or with a mixed solution of lanthanum nitrate and nickel
nitrate)overnight. The total amount of metal Ni loading was
10 wt%. The catalyst was dried, and then the dried supported
catalyst was reduced by dropwise addition of an aqueous solution
been developed for the production of hydrogen peroxide from
carbon monoxide, water, and oxygen. The experimental inves-
tigation confirmed that the promoter/Ni loading ratio and the
preparation conditions show a significant effect on the activity
and catalytic lifetime. Among all the catalysts tested, the Ni–La–
ꢁ
ꢂ
2þ
B/Al2O3 catalyst with 1 : 15 molar ratio of La/Ni, dried at 120 C,
of KBH4 (0.5 M, n (BH4 /Ni ) ¼ 3). The amorphous structures
of catalysts were determined byXRD using a Rigaku C/max-2500
diffractometer with Cu Kꢀ radiation. The reaction was conducted
in an autoclave with 350 mL distilled water containing phospho-
rous acid (the concentration is about 0.01 M)and 5 g catalyst.
Before the reaction, the pressure was increased to 3000 kPa, with
which the partial pressure of CO was 500 kPa and that of O2 was
shows the best activity and lifetime for the production of
hydrogen peroxide.
Hydrogen peroxide is a very important chemical applied for
chlorine-free bleaching. The utilization of hydrogen peroxide for
the novel green chemical synthesis has also made a great
ꢁ
2500 kPa. The reactions were carried out at 20 C. The aqueous
samples taken out were analyzed by titration using the iodometric
method.
1
{4
progress. The traditional production of hydrogen peroxide is
not an economic and simple process. A great effort has been made
worldwide towards a development of a simple but efficient
Figure 1 shows the comparative results of activities of
catalysts with different La/Ni ratios. Obviously, under the same
preparative conditions, the activity of Ni–La–B/Al2O3 (#2, #3,
and #4)was increased and prolonged, compared to the catalyst #1.
The results shown in Figure 1 also exhibit that the stability of
catalyst was improved with increase of molar ratio of La/Ni. The
lifetime of the catalyst #4 reached six hours. La has been applied
here to keep the stability of the Ni supported catalyst. It has been
considered that La atoms take up part of active sites (Ni)of Ni–B
alloys. Upon the XPS analysis using a PHI1600 XPS system, the
addition of La can significantly slow down the oxidation of Ni
under the oxidative conditions. The lifetime of the catalyst is
thereby prolonged. However, a further increase in La content
leads to a diminishing activity. The best result was obtained with
the catalyst #3.
5{8
production of hydrogen peroxide.
Among the techniques
developed, the production of hydrogen peroxide from carbon
monoxide, water, and oxygen is very promising owing to its high
safety. However a drawback in the investigation of H2O2
synthesis from CO, water, and O2 is that the palladium or other
noble metal catalysts are required.8 In addition, most of these
processes employed a complex homogeneous catalytic system
that requires extra separation process or acid additives for the
reaction. Only one work was related to the use of heterogeneous
{13
1
3
catalytic synthesis over Pd/CaCO3 and Ru/graphite catalysts.
In this work, we report an amorphous Ni oxide supported
catalyst for the production of hydrogen peroxide from CO, water,
and O2. Amorphous alloys have recently attracted much attention
for the use as catalysts,1
4{17
especially, for hydrogenation,
dehydrogenation, hydration, dehydration, and methanation of
1
6;17
carbon dioxide.
Here the capability of the amorphous Ni
alloys (or as the precursors)in the synthesis of H 2O2 from CO,
water, and O2 was well demonstrated.
Table 1 presents the catalysts applied in this work. Each
catalyst precursor was prepared by chemical reduction method.
Table 1. Amorphous catalysts used in this reaction
Preparation conditions
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Molar ratio of
No. Composition
Temperature/ C/(time/h)
for drying
La/Ni
#1
#2
#3
#4
#5
#6
Ni–B/Al2O3
120/10
120/10
120/10
120/10
60/10
Figure 1. Comparison of catalytic activities with
different La/Ni ratios.
Ni–La–B/Al2O3
Ni–La–B/Al2O3
Ni–La–B/Al2O3
Ni–La–B/Al2O3
Ni–La–B/Al2O3
1 : 20
1 : 15
1 : 10
1 : 15
1 : 15
Figure 2 presents the effect of drying temperature on catalytic
activities of catalysts with the same La/Ni ratio. From Figure 2,
ꢁ
250/10
we can see that, when drying temperature is either 60 C (#5)or
Copyright Ó 2002 The Chemical Society of Japan
Ma, Zhonglong
