Influences of particle size and crystallinity of highly loaded CuO/ZrO₂ on CO₂ hydrogenation to methanol

Abstract

In this study, highly loaded CuO (65.2 wt%) on ZrO2 support was prepared by flame spray pyrolysis, and the effects of their particle sizes and ZrO2 crystallinity on CO2 hydrogenation to methanol were investigated. By varying the precursor feed rate (1–10 mL min−1), the crystallite size (3–7 nm) and the crystallinity of tetragonal ZrO2 were controlled. After H2 reduction at 300°C, the Cu species in the catalysts, prepared at the feed rate = 2–10 mL min−1, were converted to Cu particles (approximately 10–20 nm); however, the size and crystallinity of ZrO2 remained the same. The activity and selectivity of the catalysts prepared at the feed rate = 2–3 mL min−1 were higher than those of the catalysts prepared at the feed rates = 5–10 mL min−1, because the smaller ZrO2 particles in the former provided more surface to stabilize small Cu particles and from interfacial Cu‐ZrO2 sites (active sites).

Improving the Cu/ZnO-Based Catalysts for Carbon Dioxide Hydrogenation to Methanol, and the Use of Methanol As a Renewable Energy Storage Media

“…A highly loaded CuO (65.2 wt%) on ZrO 2 support prepared by flame spray pyrolysis (FSP), showed a good catalyst activity compared with a commercial catalyst (Figure 11D). The production rate of methanol by CO 2 hydrogenation and the selectivity to methanol over FSP-made CuO/ZrO 2 catalysts were obviously higher compared with those of commercial CuO/ZnO/Al 2 O 3 (Fujiwara et al, 2019). For all catalysts, the CO 2 conversion increased, with increasing contact time, while the selectivity to methanol decreased, but the selectivity to CO increased (Figure 11E).…”

“…The former feed rate led to the formation of smaller ZrO 2 particles, which provided more surface to stabilize small Cu particles and formed interfacial Cu-ZrO 2 active sites. The crystallite size and crystallinity of t-ZrO 2 could be controlled by varying the precursor feed rate (Fujiwara et al, 2019).…”

“…The contact time of commercial CuO/ZnO/Al 2 O 3 and CuO/ZrO 2 prepared at P 1-10 ml min −1 were 60-1,500 g cat s L −1STP and 600-1,500 g cat s L −1 STP , respectively. For CuO/ZrO 2 prepared at P 3 ml min −1 , the contact time at 200-500 g cat s L −1 STP was also examined(Fujiwara et al, 2019). Reproduced with permission from John Wiley and Sons.…”

Estudo dos efeitos de estratégias de manipulação química e estrutural em catalisadores heterogêneos aplicados à hidrogenação de CO>sub<2>/sub< a metanol

“…É estabelecido por muitos pesquisadores que a diminuição no tamanho das partículas leva a um aumento da energia livre de superfície resultando em menor energia de formação de vacâncias de átomos de oxigênio e defeitos em sua superfície resultando em maior reatividade com as moléculas adsorvidas e, portanto, maior basicidade (FUJIWARA et al, 2019;GAO et al, 2013;KUMAR;OJHA, 2015;LI, YEZHOU et al, 2014;STRUNK et al, 2009;TILLEY, 2004;WANG, WEIWEI et al, 2020).…”

“…Outro ponto a ser discutido é a ocorrência de fortes interações metal-suporte entre cobre e zircônia que podem garantir altos valores de área metálica mesmo em catalisadores não revestidos, como foi observado na etapa anterior que evidenciou que os catalisadores contendo zircônia apresentaram valores de dispersão e área metálica maiores que os catalisadores do grupo contendo céria (PAN et al, 2017). (FUJIWARA et al, 2019;GAO et al, 2013;GUO et al, 2011;KUMAR;OJHA, 2015;LI, L. et al, 2015;LI, YEZHOU et al, 2014;STRUNK et al, 2009;TILLEY, 2004;WANG, WEIWEI et al, 2020). Além disso, os maiores valores dessa propriedade verificados para o catalisador CuCeIn-cs quando comparado ao material CuZrIn-cs são esperados pela alta basicidade característica dos lantanídeos em virtude de sua facilidade de doação de elétrons agindo como sítios básicos de Lewis (ZABILSKIY et al, 2015).…”