Studies on the efficient partial oxidation of butanes

在Ni_2P_2O_7中用5- 10at%的Ga、Y或Ca离子取代Ni离子，可改善异丁烷低温氧化脱氢反应。在450 ℃时，Ca离子取代10%的Ni离子的Ni_2P_2O_7催化剂的C_4H_8生成活性有所提高，10%的Y离子或Ga离子取代的Ni_2P_2O_7催化剂的C_4H_8生成活性与Ni-Ca-PO催化剂相当。对于氧的转化率，其效果并不均匀，Ni-Ga（10）-PO在430 ℃时完全消耗氧，而Ni-Y（10）-PO在450 ℃时消耗50%的氧。过渡金属的取代使结晶度减弱。用Ca取代5原子%的Ni，衍射强度降低。Ni-Ga（5%）-PO催化剂的最强峰向高角移动了0.45 μ m。这一结果按以下方式解释。Ga^<3+>离子的离子半径为6.2nm，Ni^<2+>离子的离子半径为6.9nm。用Ga^<3+>取代Ni^<2+>，三分之二的Ni^<2+>位置被Ga^<3+>占据，三分之一是空位。这导致晶格孔隙率的减少。XRD和XPS数据表明，部分过渡金属离子位于晶格中。在450 ℃时，催化剂的催化活性与催化剂的酸量无关，在450 ℃时，催化剂表面氧的活化是催化活性的关键因素。

Substitution of 5-10 atomic% of Ga, Y,or Ca ions for Ni ions in Ni_2P_2O_7 improved the oxydative dehydrogenation of iso-butane at the low temperatures. Ni_2P_2O_7 in which 10% of Ni ions were substituded by Ca ions increased the activity of C_4H_8 formation at 450ﾟC.Ni_2P_2O_7 substituted by 10% Y ions or Ga ions showed the same activity as to that of the Ni-Ca-PO catalyst. As for the oxygen conversion, the effects are not uniform, oxygen was completely consumed over Ni-Ga(10)-PO at 430ﾟC.On the other hand, 50% of oxygen was consumed over Ni-Y(10)-PO at 450ﾟC.The optimun oxygen concentration in the feed was 5-10 atomic%. Substitution by transition metals made the crystallinity weakened. The diffraction intersity decreased by the substitution of 5 atomic% of Ni by Ca. The most intense peak of Ni-Ga(5%)-PO catalyst is shifted to higher angle by 0.45 of 2 rheta. This results are accounted for the following manner. Ionic radius of Ga^<3+> ions, 6.2nm, is smaller than taht of Ni^<2+>,6.9nm. Substituting Ni^<2+> by Ga^<3+>, two thirds of removed Ni^<2+> sites are occupied by Ga^<3+>, and one thirds is vacant. This lead to the reduction of lattice porameter. It is concluded from the XRD and XPS data that a part of transition metal ions are located in the crystal lattice. The catalytic activety of these catalysts such as 450ﾟC is independent to the acid amounts of the catalyst measured by NH_3 TPD.At low temperatures such as 450ﾟC,activation of oxygen on the catalyst surface is a key factor in the catalysis.