A route to drastic increase of CO2 uptake in Zr metal organic framework UiO-66

Abstract

CO2 uptake in zirconium MOF UiO-66 almost doubles with post-synthetic exchange of Zr by Ti. This was due to smaller pore size and higher adsorption enthalpy, with good complementarity between experiment and simulation. Furthermore, the full effect is obtained with ~50% Ti loading, precluding the need to fully substitute frameworks for CO2 capture.

Postsynthetic Modification of Zirconium Metal‐Organic Frameworks

“…Transmetalated UiO‐66 samples containing Ti IV were subsequently investigated for their ability to improve CO 2 uptake capacities . UiO‐66 samples containing Ti IV loadings as high as 56 mol‐% were obtained [denoted UiO‐66(Ti 56 )] by allowing the transmetalation process to occur over a longer period of time.…”

“…a) Increasing isosteric heats of adsorption for CO 2 in UiO‐66 as more Zr is exchanged for Ti. Reproduced (modified) with permission from ref . Copyright (2013) Royal Society of Chemistry.…”

Mixed‐Metal MOFs: Unique Opportunities in Metal–Organic Framework (MOF) Functionality and Design

“…Metal exchange is often carried out by stirring the homometallic parent MOF with the second metal ion of choice in aliquid solution in which partial replacement of metal in parent MOF can be tuned by controlling synthetic parameters,s uch as concentration, reaction time and exchange temperature ( Figure 10). [21,74,[77][78][79][80] Thepossibility of the metal exchange to prepare MM-MOF is based on the well-established reversibility of the metal-ligand bond that is behind the synthesis of MOFs with high crystallinity and the use of modulators. [81] One of the most widely reported metal replacement corresponds to Zr-based MOFs that are modified by exchange with Ti IV or Hf IV ions ( Figure 11).…”

“…[81] One of the most widely reported metal replacement corresponds to Zr-based MOFs that are modified by exchange with Ti IV or Hf IV ions ( Figure 11). [21,82] Evidence in favor of the success of the metal ion exchange is mainly based on chemical analysis of the liquid as well as the MM-MOF.However, these data are insufficient to locate the exchanged sites and much more detailed structural characterization is needed. Thus,int he case of Ti IV , recent characterization by TEM-EDX has cast doubts about the…”

“…[16] Thep resence of more than one metal in the nodes or immobilization of metal ions,m etal nanoparticles, metal complexes,and organometallic compounds inside MOF cavities as guests with or without interaction with the MOF framework are particular cases of heterogeneity in MOFs and according to Chensd efinition of MM-MOFs will be the subject of the present Minireview. [17][18][19][20][21][22] These MOFs containing more than one metal somewhere in their structure offer opportunities in terms of multifunctionality and tuning of the properties of the material to ag iven application. As ar esult of the synergistic effects that could derive from the presence of two or more metals,M M-MOFs can exhibit better performance in various applications compared to single-metal MOFs particularly in gas storage and separation, heterogeneous catalysis,s ensing,a nd construction of photoactive materials.…”