The Rise of Calcination Temperature Enhances the Performance of Cu Catalysts: Contributions of Support

Abstract

To develop the high-performance supported metal catalyst for industrial processes, it is highly desirable to elucidate and fully utilize the indispensable support part. Herein, the relationship between catalytic performance and the structure of support ZrO2 was elucidated by comprehensive analysis of the progressive calcination experiments, tests over model catalysts, and various characterizations of catalyst structures. We demonstrated that combination of Cu and tetragonal ZrO2 makes a highly active, selective, and especially stable catalyst for the hydrogenation of dimethyl oxalate to ethylene glycol. To obtain stable Cu particles, the catalyst was annealed at high temperatures (e.g., from 450 to 850 °C). The stable large Cu particles were formed, and the number of exposed Cu sites decreased. Fortunately, support ZrO2 was motivated into the tetragonal phase, compensating for and even improving the activity. Thus, the yield of ethylene glycol was greatly improved from ∼26 to 99%, and a stable performance was achieved (life span of >600 h). The strategy alleviated the dependence of hydrogenation on highly dispersed metal sites and provided an alternative way to enhance the catalytic stability. This simple way simultaneously improved the efficiency and reduced the level of irreversible deactivation due to sintering, which has great potential for industrial applications. Tetragonal ZrO2 also proved to be effective for a series of carbonyl hydrogenations (e.g., esters, aldehydes, ketones, and acids), indicating a general promotion of these reactions by ZrO2.

Efficient synthesis of 2,5-dihydroxymethylfuran and 2,5-dimethylfuran from 5-hydroxymethylfurfural using mineral-derived Cu catalysts as versatile catalysts

“…17,18 Ru-modified Cu/MgO/Al 2 O 3 catalysts were reported for HMF hydrogenation with high reactivity. [24][25][26] ZnO, as a catalyst support, has moderate surface acidity, facilitating the possibility of tunable synthesis of DHMF and DMF. Control of surface acidity is also crucial.…”

New Catalysts for Coal to Ethylene Glycol

“…Due to the high reaction activity and low cost, Cu-based catalyst has been widely used in DMO hydrogenation to EG. [33][34][35][36] …”

“…The other supports can be divided into two categories: simple oxides (TiO 2 , [52] ZnO, [53] Al 2 O 3 , [54] ZrO 2 [55] etc.) and molecular sieves (SBA-15, [56] ZSM-5, [57] MCM-41, [58] HMS, [59] etc.).…”

“…[54] Zhu et al also reported a tetragonal ZrO 2 supported Cu-based catalyst, which exhibited a high activity, and stability for DMO hydrogenation to EG. [55] Many molecular sieves such as SBA-15, ZSM-5, MCM-41, HMS etc. are used as supports to achieve high dispersion of Cu species, which is responsible for the superior catalytic performance of molecular sieves supported Cu based catalysts.…”

Effect of Different Nano-Sized Silica Sols as Supports on the Structure and Properties of Cu/SiO2 for Hydrogenation of Dimethyl Oxalate

“…Increasing the dispersion of active copper and bond strength between support and active component is beneficial for preventing the agglomeration and sintering of active copper. Silica [6,7], alumina [8], zirconia [9], titania [10], and other supports [11,12] can be used for…”