Decomposition of CCl4 on CaO

Koper, Olga B.; Wovchko, Edward A.; Glass, John A.; Yates, John T.; Klabunde, Kenneth J.

doi:10.1021/la00006a035

Cited by 48 publications

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“…[8][9][10][11] Alkaline-earth metal oxides and lanthanide oxides convert CHCs into Ocontaining products, for example CO 2 . [12][13][14][15][16][17][18][19][20][21][22][23][24][25] This process, known as destructive adsorption, involves exchange of the Cl atoms of the CHC with the lattice O atoms of the metal oxide. As a result, the metal oxide is partially or completely converted into the corresponding metal chloride.…”

Section: Introductionmentioning

confidence: 99%

Intermediates in the Destruction of Chlorinated C₁ Hydrocarbons on La‐Based Materials: Mechanistic Implications

Heijden

Ramos

Weckhuysen

2007

Chemistry A European J

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Activity experiments using GC analysis of reactor effluent have been combined with in situ IR spectroscopy to elucidate the reaction steps in the destructive adsorption of CHCl3, CH2Cl2, and CH3Cl over LaOCl. The IR results show that during reaction, LaOCl is covered with carbonate, formate, and methoxy groups. The relative amount of each of these surface intermediates depends on the Cl/H ratio of the reactant. The decomposition of the surface species leads to formation of the reaction products, and is influenced by the temperature and the relative amount of Cl present on the surface. The GC results show that the activity for the destructive adsorption of H‐containing chlorinated C1 compounds decreases with increasing hydrogen content of the reactant. The acquired insight into the mechanism of destructive adsorption is crucial to the design of new catalyst materials for the efficient conversion of chlorinated hydrocarbons into nonhazardous products or reusable chemicals.

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Section: Introductionmentioning

confidence: 99%

Intermediates in the Destruction of Chlorinated C₁ Hydrocarbons on La‐Based Materials: Mechanistic Implications

Heijden

Ramos

Weckhuysen

2007

Chemistry A European J

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“…Potential materials involve alkaline earth metal oxides, lanthanide oxides, and transition metal oxides, and the process of destructive adsorption of chlorinated hydrocarbons has been studied for all these compounds by Klabunde and co-workers [3][4][5][6][7][8] and several other groups. [9][10][11][12][13][14][15][16] In this reaction, the solid material is chlorinated, while the chlorinated hydrocarbons are oxidized to, e.g., CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Destructive Adsorption of CCl₄ over Lanthanum-Based Solids: Linking Activity to Acid−Base Properties

et al. 2005

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The relative activities of a low-surface crystalline and high-surface amorphous LaOCl, further denoted as S1 and S2, have been compared for the destructive adsorption of CCl 4 . It was found that the intrinsic activity of S2 is higher than that of S1. Both samples were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 -physisorption, and Raman and infrared (IR) spectroscopy. IR was used in combination with CO 2 , CO, and methanol as probe molecules. The CO 2 experiments showed that different carbonate species are formed on both materials. For S1, a high surface concentration of bidentate carbonate species and a lower concentration of monodentate carbonate were observed. In the case of S2, bulk carbonates were present together with bridged carbonates. CO adsorption shows that S2 and S1 have very similar Lewis acid sites. However, methanol adsorption experiments showed that S2 had a higher number of stronger Lewis acid sites than S1 and that twofold coordinated methoxy species were more strongly bound than threefold coordinated methoxy species. Because of the analogy between methanol dissociation and the removal of the first chlorine atom in the destructive adsorption of CCl 4 , the sites enabling twofold coordination were likely to be the same Lewis acid sites actively involved in the destructive adsorption of CCl 4 . La 2 O 3 was less active than the two LaOCl materials, and therefore, the intrinsic activity of the catalyst increases as the strength of the Lewis acid sites increases. S2 contains more chlorine at the surface than S1, which is expressed by the higher number of sites enabling twofold coordination. Moreover, this explains the difference in destructive adsorption capacity for CCl 4 that was observed for the samples S1 and S2. Since LaCl 3 , being the most acidic phase, is not active for the destructive adsorption of CCl 4 , basic oxygen atoms, however, remain needed to stabilize the reaction intermediate CCl 3 as La-O-CCl 3 .

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“…An example of the unusual reactivity of nanomaterials and how it has been exploited for the benefit of the environment is found in the work of Klabunde's group [3][4][5][6]. For the last 10 years, this group has systematically studied the destruction of halogenated hydrocarbons by nanoparticulate metal oxide aerogels (e.g., CaO).…”

Section: Acid-base Chemistrymentioning

confidence: 99%

Nanomaterials for Environmental Remediation

Fryxell

Mattigod

2003

Nanotechnologies for the Life Sciences

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The sections in this article are Introduction Nanoparticle‐based Remediation Materials Acid–Base Chemistry Redox Chemistry Field Deployments of ZVI Absorption Chemistry Hybrid Nanostructured Remediation Materials Nanostructured Metal Phosphonates Iminodiacetic Acids and Related Chelating Ligands Macrocycle Metal Phosphonates Self‐assembled Monolayers on Mesoporous Supports ( SAMMS ) Thiol SAMMS Performance with Actual Waste Thiol SAMMS Performance on Contaminated Oil Anion SAMMS Actinide SAMMS Functional CNTs Conclusions

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Decomposition of CCl4 on CaO

Cited by 48 publications

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Intermediates in the Destruction of Chlorinated C₁ Hydrocarbons on La‐Based Materials: Mechanistic Implications

Intermediates in the Destruction of Chlorinated C₁ Hydrocarbons on La‐Based Materials: Mechanistic Implications

Destructive Adsorption of CCl₄ over Lanthanum-Based Solids: Linking Activity to Acid−Base Properties

Nanomaterials for Environmental Remediation

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Decomposition of CCl4 on CaO

Cited by 48 publications

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Intermediates in the Destruction of Chlorinated C1 Hydrocarbons on La‐Based Materials: Mechanistic Implications

Intermediates in the Destruction of Chlorinated C1 Hydrocarbons on La‐Based Materials: Mechanistic Implications

Destructive Adsorption of CCl4 over Lanthanum-Based Solids: Linking Activity to Acid−Base Properties

Nanomaterials for Environmental Remediation

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Intermediates in the Destruction of Chlorinated C₁ Hydrocarbons on La‐Based Materials: Mechanistic Implications

Intermediates in the Destruction of Chlorinated C₁ Hydrocarbons on La‐Based Materials: Mechanistic Implications

Destructive Adsorption of CCl₄ over Lanthanum-Based Solids: Linking Activity to Acid−Base Properties