Influence of calcination procedure on the catalytic property of sulfated zirconia

Li, Xuebing; Nagaoka, Katsutoshi; Simon, Laurent; Olindo, Roberta; Lercher, Johannes A.

doi:10.1007/s10562-006-9005-5

Cited by 20 publications

(11 citation statements)

References 27 publications

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“…5 Other authors also indicated the importance of labile sulfate groups for activity. 22 Contrary to some zirconia samples, sulfated by a procedure similar to that applied in this work, in which the amount of incorporated sulfates were directly proportional to the surface area of the SZ, 20 all the samples investigated in this study had the same amount of sulfates, i.e., 4.2 mass %, Table II. 7 In addition, the procedure of the calcination step seems to be important.…”

Section: Resultsmentioning

confidence: 81%

Temperature imposed textural and surface synergism affecting the isomerization activity of sulfated zirconia catalysts

Zarubica

Jović

Nikolić

et al. 2009

JSCS

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Using sulfuric acid as the sulfating agent, two catalyst series were obtained from hydroxide and nitrate precursor with a sulfate loading identical to commercial sulfated hydroxide, i.e., 4.2 mass %. After calcination at 500, 600 and 700 °C, all nine samples had various contents of residual sulfates depending on the origin of the catalyst. Accordingly, their surface properties were different, which, together with various textural properties, govern the formation of the active phase and their catalytic activity in the n-hexane isomerization reaction. The dominant activity and yield of mainly mono-branched isomers were attained in reaction at 200 °C with a commercially sulfated zirconia catalyst calcined at 500 °C. Among the SZ catalyst series synthesized from hydroxide and nitrate, the second according to its activity profile was similar to that of the commercially sulfated one, while samples originating from hydroxide showed some activity only after calcination at 600 °C. This is due to the poorer textural properties of the hydroxide series, necessitating a higher calcination temperature in order to promote the simultaneous decomposition of S-containing species and their re-adsorption into the zirconia matrix following interaction and active phase formation. It seems that the tetragonal zirconia phase was not responsible for the catalytic activity but a synergistic effect of the textural properties of the samples and the sulfate loadings, which determine different acid strengths on the catalyst surface.

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Section: Resultsmentioning

confidence: 81%

Temperature imposed textural and surface synergism affecting the isomerization activity of sulfated zirconia catalysts

Zarubica

Jović

Nikolić

et al. 2009

JSCS

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“…This promoting effect of nonspecific olefins addition indicated that the alkene may be one of the intermediates in alkane isomerization because of its higher reactivity to form carbenium ion species than alkane . Nevertheless, SZ‐based material still exhibited isomerization activity after removing all alkenes in the raw, implying the in situ generation of olefins on the SZ surface. At this point, the alternative oxidative dehydrogenation (ODH) activation of alkane on SZ surface was proposed and evidenced.…”

Section: Activation Of Alkane Over Sulfated Zirconiamentioning

confidence: 99%

“…This implied a strong chemical interaction between sulfate species and amorphous zirconia was formed during the calcination, which facilitated the formation of tetragonal zirconia and highly active sites. Indeed, the calcination protocol strongly affected the n ‐alkane isomerization activity . Chen et al suggested that the formation of active sites involved a two‐step surface reaction between sulfate species and superficial hydroxyl groups of zirconium hydroxide:

Zr {(OH)}_{4n} + {xH}_{2} {SO}_{4} \to Zr {(OH)}_{4n - 2x} {({SO}_{4})}_{x} + {2xH}_{2} normalO

Zr {(OH)}_{4n - 2x} {({SO}_{4})}_{x} \to {ZrO}_{2n - normalx} {({SO}_{4})}_{x} + ((), 2n - normalx) H_{2} normalO

…”

Section: Determination Of Intrinsic Structure‐reactivity Relationshipmentioning

confidence: 99%

Alkane isomerization over sulfated zirconia solid acid system

et al. 2020

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Summary Sulfated zirconia (SZ) and its modified versions attract great interest in recent years, because of their promising potential in n‐alkane isomerization. The oxidative and protonation routes are active and interactional in n‐alkane activation over SZ catalysts. The bimolecular reaction becomes dominant with increasing the density of active sites on SZ surface and decreasing the carbon chain of feed. Pentane and hexane are mainly isomerized by protonated cyclopropane mechanism, while which is thermodynamically unflavored for n‐butane isomerization. The deactivation of SZ catalysts is primarily caused by the loss of superacidity and oxidizing ability, resulted from the structure changes of sulfate species. Several strategies for improving the activity of SZ are reviewed. The intrinsic structure‐reactivity relationship of SZ catalysts in alkane isomerization is updated to illuminate the prerequisite for the highly active catalysts and the mechanism of active sites formation. The applications of Pt/SZ in fixed‐bed and unmodified SZ in circulating fluidizing bed in light alkanes isomerization are compared with the conventional technologies based on the chlorinated alumina catalysts. Finally, the future study of SZ catalysts is outlooked from the academic investigations to the industrial applications.

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“…Pyrosulfates are generally considered to be the most important species for activation and conversion of n-butane, [44] therefore DRIFTS was employed to investigate the sulfate structure. Figure 3 shows the DRIFT spectra obtained.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, these species seem to be minority species which initiate the reaction at high conversion levels for Cat_SZ1, whereas no activity was observed for Cat_SZ2. The initial step of the reaction cycle was proposed, by Li et al, [44] to be a stoichiometric redox reaction. The assumption of a minority species being responsible for initializing the isomerization reaction was also established by Breitkopf et al [47] by selective poisoning of surface centers.…”

Section: Resultsmentioning

confidence: 99%

An Integrated Catalytic and Transient Study of Sulfated Zirconias: Investigation of the Reaction Mechanism and the Role of Acidic Sites in n‐Butane Isomerization

Breitkopf¹

2009

ChemCatChem

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The transient temporal analysis of products (TAP) pulse method has been applied to investigate the isomerization of n‐butane on sulfated zirconias at very low pressure. By combining these results with findings from XRD, XPS, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), temperature‐programmed desorption (TPD), and catalytic studies at atmospheric pressure, a wide range of pressure conditions can be accessed to study the influence of surface sulfate groups on the isomerization activity and the mechanism of this reaction. The catalytic activity of powder catalysts has been correlated to the surface site density of sulfates, with pyrosulfate structures playing a major role in the initiation of the reaction. The complex interplay between sulfate‐free and sulfate‐covered zirconia surfaces for the adsorption of alkanes has been investigated in detail, with TAP pulse experiments showing a monomolecular reaction pathway at low n‐butane partial pressures. Moreover, TAP pulse experiments have allowed detection of the reaction products of this initiation process, including butene and water, and have shown their influence on the deactivation of sulfated zirconias. Heats of adsorption have been calculated from the TAP pulse experiments.

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Influence of calcination procedure on the catalytic property of sulfated zirconia

Cited by 20 publications

References 27 publications

Temperature imposed textural and surface synergism affecting the isomerization activity of sulfated zirconia catalysts

Temperature imposed textural and surface synergism affecting the isomerization activity of sulfated zirconia catalysts

Alkane isomerization over sulfated zirconia solid acid system

An Integrated Catalytic and Transient Study of Sulfated Zirconias: Investigation of the Reaction Mechanism and the Role of Acidic Sites in n‐Butane Isomerization

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