Selective hydroisomerization of isobutane to n-butane over WO3-ZrO2 supported Ni-Cu alloy

To develop a robust and efficient non-noble metal-based catalyst for selective hydroisomerization of short-chain iso-alkanes is of great importance, yet challenging. In the present studies, a series of WO3-ZrO2 supported Ni, Cu catalysts were prepared by incipient wetness impregnation. The characterization results of Mapping, XRD, H-2-TPR, TEM, and XPS confirmed the formation of Ni-Cu alloy in the bimetallic catalysts. The results of NH3-TPD indicated that the formation of Ni-Cu alloy increased the amount of medium acidic sites and total acidic sites. Isobutane hydroisomerization to n-butane was used as probe reaction to evaluate the catalytic activity. With the Cu addition up to 1 wt% over 1 wt% WO3-ZrO2, the hydrocracking reactions were inhibited, leading to both a significant increase in the selectivity to n-butane and an improved stability of the catalysts. Under the optimized condition, the yield of n-butane was 38.86% at 450 degrees C, 2.5 MPa with an H-2/alkane of 4:1, and a LHSV of 1 h(-1) over 1Ni1Cu/WZr. The activity of 1Ni1Cu/WZr remained almost unchanged after 123 h on stream. A possible reaction scheme was also proposed for the isobutane hydroisomerization to n-butane over 1Ni1Cu/WZr.