Conversion of n-butane on H-mordenite catalysts

Conversion of n-butane on various mordenite catalysts have been studied at temperatures ranging within 150–500°C. The isomerization activity of the catalysts is shown to depend on the temperature, mordenite composition and its molar ratio of SiO₂/Al₂O₃.

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150–500°C - H-, . , , SiO₂/Al₂O₃.

     

低结焦渣油催化裂化催化剂的制备及其性能

 采用联合脱铝法制备了一系列高硅铝比Y型沸石FSY,并对其加La老化的LaFSY催化裂化性能进行了研究. 结果表明, (NH4)2SiF6处理和水热处理两个步骤联合可有效调节FSY沸石的酸密度,所得LaFSY沸石具有适量强酸位和较少弱酸位,在保持高微反活性的同时有效地降低了重油结焦率. 以大庆常压渣油为裂化原料,与另一种广泛使用的工业催化剂相比,该LaFSY沸石为活性组分的微球催化剂可使轻质产品收率由85.4%提高到88.9%, 而结焦率由9.0%下降到7.5%.     

结焦催化剂上焦炭氢碳比的测定方法

提出了一种测定裂化结焦催化剂上焦碳H/C的方法--酸溶-元素分析法。该方法主要利用HF和HCl将焦碳从催化剂上进行剥离，然后利用元素分析仪测定焦碳中的碳含量和氢含量，从而可以得到结焦催化剂上焦碳的H/C质量比。这种测定方法避免了在测氢过程中催化剂结晶水和吸附水对测定结果的影响，大大提高了催化剂上焦碳H/C的测定精度。     

On the mechanism of n-butane conversion on H-mordenite

It is suggested that n-butane isomerization on H-mordenite takes place via a step of disproportionation due to the increased acidity of the latter. This suggestion is confirmed by a comparison between the product distribution of n-butane and C₈ hydrocarbons (n-octane and isooctane) in the presence of dealuminated mordenite containing no Pt group metals.

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, - - , . - C₈ (-qo ) , , .

     

Isomerization of m-xylene on H-mordenite and H-clinoptilolite catalysts

The catalytic properties of Hungarian natural H-mordenite and H-clinoptilolite were studied. The accompanying substances in the rock were found to be catalytically inactive in the reaction investigated. The active centers of clinoptilolite and mordenite are the OH groups with IR bands at 3610 and 3600 cm^–1, respectively. In the case of activation above 550 °C, active sites are also the Lewis centers formed during dehydroxylation. The initial rate of m-xylene isomerization can be described by a Langmuir type equation. In a single reaction step the shift of the methyl groups occurs only between two neighboring carbon atoms of the benzene ring.

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H- H-. , . — OH - 3610 3600 ^–1, . 550 °C . . - . .

     

Frequencies, anharmonicities, and dissociation energies of OH groups in H-mordenite

Harmonic frequencies, anharmonicities and dissociation energies of surface hydroxy groups in H-mordenite have been determined. The application of the Lippincott-Schroeder potential function for similar problems is proposed.

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, -. - .

     

Bi-Pt催化剂在H-mordenite载体上的甘油选择性氧化

以Bi-Pt/H-mordenite为催化剂,对甘油(GLY, Glycerol)选择性氧化制备二羟基丙酮(DHA, Dihydroxyacetone)进行了研究。采用BET对催化剂进行表征,结果表明,催化剂的比表面积对催化剂的反应性能影响较小。甘油的裂解是主要的副反应,而H-mordenite可以抑制甘油的裂解,提高DHA的选择性。最佳反应条件为温度353 K,反应时间2~4 h,空气流量20 mL/min,甘油(水-乙醇1:1混合溶液的质量分数为10%),催化剂为1%Bi-5%Pt/H-mordenite时,甘油的转化率为70.6%,DHA的选择性为61.0%。     

Effects of binder, coking and regeneration on acid properties of H-mordenite during TDP reaction

The effects of binder, coking and regeneration on the acid properties of H-mordenite zeolite during toluene disproportionation reaction (TDP) have been investigated by solid-state ³¹P-MAS-NMR of various adsorbed phosphorous probe molecules in conjunction with elemental analysis by ICP-MS technique. A series of fresh, spent and regenerated mordenite-based commercial catalysts were examined and the results were also compared with binder-free H-mordenite zeolite and unformulated γ-alumina binder. It is found that parent H-mordenite zeolite possessed only Brønsted acidity, which is responsible for the observed catalytic activity. In contrast, the γ-Al₂O₃ binder exhibited only Lewis acidity and plays a minor role during the catalytic reaction. While the amount of strong Brønsted acid sites decreased rapidly during initial coking, it reached a plateau at a total coke content of ca. 7 wt%, corresponding to ca. 80% decrease in total acidity. That the catalyst remained active even under deep coke deposition (>7 wt%) condition indicated catalytic activity may be invoked by subsequent coking taking place on the external surface rather than intracrystalline channels of the zeolite catalyst. Furthermore, upon catalyst regeneration treatment, ca. 75% of the total acidity could be effectively recovered.     

Anion-radical formation in the adsorption of thiophene and its derivatives on H-mordenite

For the first time it has been established that the adsorption of thiophene and its derivatives on H-mordenite provides individual ESR signals with an hyperfine structure. A comparison of the experimental ESR spectra with the calculated magnetic resonance parameters permits to suggest that during the adsorption on HM anion-radicals of thiophene and its derivatives are formed.

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, HM . , HM - .

     

Study of hydroisomerization of n-hexane on natural mordenite catalyst

A mordenite-containing rock sample from the Tokaj Mountains (Hungary) and its various forms modified by chemical treatment have been tested for catalytic properties during isomerization of n-hexane. Addition of Pt to the catalyst leads to a sharp decrease in the rate of cracking and in the rate of deactivation and this results in a catalyst of high selectivity for hexane isomers.

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(), , , , -. Pt , .

     

The adsorption of benzene and n-hexane on aluminum oxide

Summary Benzene is physically adsorbed on Al₂O₃ at 20–100° in greater amount than is n-hexane. In the range 100–150°, chemisorption of both hydrocarbons begins and decreases with increase in temperature.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 900–902, May, 1965 Original article submitted July 22, 1964     

用IR/TPD法测定氢型丝光沸石上氨的脱附活化能

通过IR/TPD的改进方法, 测定了氨在氢型丝光沸石(HM)上的Bronsted酸位上的脱附活化能和相应的集居数。结果表明, 在HM上有三种不同强度的Bronsted酸位, 分别对应脱附活化能为63.6、49.8和35.4kJ/mol。     

The influence of adamantane on the reaction of n -heptane over H-Y, H-β and H-mordenite zeolites

The effect of adamantane (Ad) on the activity and selectivity of acidic zeolites Y, β and mordenite (M) in the isomerization and cracking ofn-heptane (C₇) in He at 443 K was studied.Ad was found to promote the isomerization of C₇. TheAd uptake of the zeolites, and the IR spectra obtained from the zeolite-boundAd were determined. It was found thatAd did not remain completely unconverted under the conditions of the C₇ reaction. The activity of the catalysts in the conversion ofAd increased in the sequence of H-Y<H-β<H-M. Existing data suggest that a fraction of theAd, responsible for the cocatalytic effect, can participate in hydride transfer processes and remain unconverted, while another fraction, depending on catalyst acidity, is converted to dimer and oligomers.