**Nickel-Modified TS-1 Catalyzed the Ammoximation of Methyl Ethyl Ketone**

### **Dandan Yang, Haiyan Wang, Wenhua Wang, Sihua Peng, Xiuzhen Yang, Xingliang Xu \* and Shouhua Jia \***

College of Chemistry and Material Science, Shandong Agricultural University, Tai'an 271018, China; 2017110585@sdau.edu.cn (D.Y.); why15053865003@163.com (H.W.); w17863807408@163.com (W.W.); psh18865383970@163.com (S.P.); x976360872@163.com (X.Y.)

**\*** Correspondence: xxlsdau@163.com (X.X.); shjia@sdau.edu.cn (S.J.); Tel.: +86-0538-824-1570 (S.J.)

Received: 5 November 2019; Accepted: 29 November 2019; Published: 4 December 2019

**Abstract:** In this paper, five kinds of transition metal-modified titanium silicalite-1 (M-TS-1) were prepared by an ultrasonic impregnation method. We studied their catalytic performances in the ammoximation of methyl ethyl ketone (MEK). The various M-TS-1 catalysts revealed distinct di fferences in their MEK ammoximation activity. The nickel-modified TS-1 (Ni-TS-1), especially 3 wt % Ni-TS-1, exhibited a satisfactory conversion of MEK (99%) associated with a high selectivity of methyl ethyl ketoxime (MEKO) (99.3%), which was 6% higher than that of TS-1 under the same conditions. Moreover, the catalyst showed excellent recyclability and the reactivity could be completely recovered after regeneration. The catalysts were characterized by Powder X-ray Di ffraction (XRD), Fourier Transformed Infrared Spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), and so on. It was demonstrated that the skeleton structure of TS-1 was basically maintained and the electron environment of the Ti active site was changed after the nickel modification, which can optimize the adsorption capacity and the activation for H2O2. Meanwhile, the surface nickel species reduced the surface acidity of the catalyst, which provided an appropriate pH and inhibited the deep oxidation of oxime.

**Keywords:** TS-1; nickel-modified; methyl ethyl ketone; ammoximation; methyl ethyl ketoxime
