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2-Methyl-3-butyn-2-ol underwent almost exclusively dehydration to 3-methyl-3-buten-1-yne (acid activity) on pure AlPO4, whereas its modification with cesium oxide developed AlPO4-based materials with increased basic properties and hence, high selectivities to the base-catalyzed cleavage of MBOH yielding acetone and acetylene. At the same conversion level, catalysts obtained from cesium chloride exhibit higher selectivities to the base-catalyzed process than those obtained from cesium acetate.

The skeletal isomerization of 3,3-dimethyl-1-butene over AlPO4 (Al/P=1), CrPO4 (Cr/P=1), and CrPO4−AlPO4 (CrAlP, 5–10 wt.% AlPO4) catalysts is a first order reaction. Catalytic performance is affected by the precipitation agent. CrPO4 catalysts obtained in propylene oxide-aqueous ammonia showed the highest activity. Moreover, the incorporation of AlPO4 to CrPO4 developed CrAlP catalysts that exhibited increased activity, irrespective of the precipitation method, as compared with both AlPO4 and CrPO4 catalysts. Besides, CrAlP catalysts prepared in propylene oxide-aqueous ammonia were the more active ones.

The vapor-phase catalytic alkylation of phenol with dimethyl carbonate over different AlPO4 (Al/P=1), Al2O3 and AlPO4-Al2O3 (5–25 wt.% Al2O3) catalysts produces anisole (O-alkylation) as the major reaction product althougho-cresol (C-alkylation) and methylanisoles were also found. The reaction is first order in phenol while O-and C-alkylation follow parallel processes. As compared with methanol, DMC is far more effective as a methylating agent, and the methylation proceeds at a lower temperature and with higher O-alkylation selectivity.

The product distributions from bifunctional conversion ofn-decane over Pt/SAPO-5 and Pt/SAPO-11 catalysts are compared in detail. Selectivities in decane reaction vary largely with the catalyst employed: Pt/SAPO-11 produces high yields of feed isomers, whereas Pt/SAPO-5 gives high yields of cracked products and only under mild reaction conditions are isodecanes the main products obtained. These selectivities seem to be determined by the structure of the catalyst.

The effects of surface dehydration on textural properties, crystallinity and the structure of AlPO4−ZrO2 (weight ratio AlPO4/ZrO2=3) systems precipitated with ethylene oxide have been studied by N2 adsorption and XRD measurements. The increase in calcination temperature in the range 773–1273 K decreases the textural parameters as a consequence of AlPO4 crystallization to the tridymite form.

The adsorption of normal and α-methylated series arenes on rhodium supported on two kinds of AlPO4 has been studied by using a gas-solid chromatographic technique. The adsorption process was exothermic (δHads 0) the relative adsorption constants being fitted to the Pavelich-Taft equation in which the electrical effect of the alkyl substituent is the main influence.

The liquid-phase catalytic hydrogenation of various organic compounds was carried out using new rhodium catalysts supported on AlPO4−SiO2 (20∶80 wt. %) system, in methanol as solvent, under low hydrogen pressure (0.55 MPa) and at 293 K. Neither alkene isomerization nor hydrogenolysis products were detected in any of the cases.

This study concerns the effect of SO42− (1–10 wt.%) on the surface acid properties of AlPO4 catalysts obtained in aqueous ammonia and based on their catalytic activity in cyclohexene skeletal isomerization (CSI) by using the Bassett-Habgood equation for first order processes. It has been found that AlPO4−SO42− catalysts are much more active in the isomerization process than AlPO4 catalysts, indicating a strongly increased acidity. Maximum catalytic activity was reached at about 2–3 wt.% and varied with further temperature treatment. Furthermore, the sulfate loading brought about a very pronounced increase in crystallinity even at the smallest content.

Highly chemoselective reduction of α, β-unsaturated carbonyl compounds (Ph−CH=CH−COR, E isomer) is obtained by using Rh/AlPO4 catalysts. The reactions carried out in liquid-phase under low hydrogen pressure (0.55 MPa) and at 298 K were found to be highly selective towards the formation of the conjugate reduction product (the saturated compound). In no cases could any appreciable amount of allylic or saturated alcohol be detected.

The liquid-phase hydrogenation of Ph−CH=CH−R substrates (E isomer) has been studied using rhodium supported at 1 wt% on two AlPO4 and an AlPO4−SiO2 catalyst. The reaction is zero order with respect to the substrate and first order with respect to hydrogen. The reaction rate has been found to be dependent on the support used, although the selectivity of the C−C double bond hydrogenation is 100%, except for E-3-phenyl-2-propen-1-ol and Ecinnamaldehyde which produce parallel isomerization-hydrogenolysis and undergo strong adsorption on the catalyst surface (autopoisoning), respectively. There is not a clear relationship between the electric or steric effects and the reaction rate.

The presence of urea during the gelling of AlPO4−Al2O3 catalysts (AlPO4/Al2O3 weight ratio =3) has been studied with respect to its effect on the porous texture and surface acidity of the resulting gels. An increase in pore volume and mean pore radius with no modification in surface acidity is found when the AlPO4−Al2O3 catalyst is modified by the addition of 5 mol% urea in the AlPO4 solution.

A kinetic study of the regeneration of a series of AlPO4, SiO2 and AlPO4−SiO2 supported nickel catalysts poisoned with n-butanethiol (nBSH) has been carried out using 1-hexene hydrogenation as the test reaction. The regeneration capacity of catalysts fits the expression $$r_A /r_A^o = e^{ - \beta \alpha _s } $$ , where rA/r A o is the regeneration capacity, αs the specific poisoning coefficient and β a constant for each series of supported catalysts, Ni/SiO2, Ni/AlPO4 and Ni/AlPO4−SiO2 (5–20 wt.%), respectively.

The use of AlPO4−ZrO2 (weight ratio AlPO4/ZrO2=3) as catalyst systems obtained with ethylene oxide and subjected to different stages of heat treatments has been studied through their catalytic activity in the skeletal isomerization of cyclohexene to 1- and 3-methylcyclopentenes (1- and 3MCP). The apparent rate constants and selectivity to 1-MCP are used for an evaluation of the presence and amount of strong acid sites, the only ones capable of giving rise to skeletal isomerization. The decrease in catalytic activity as calcination increases is consistent with not only the decrease in the amount of acid sites measured vs. weaker organic bases but also with the decrease in Bronsted acidity, as shown by the decrease in O−H band intensity.

The surface acidity and basicity of AlPO4-ZrO2 (weight ratio AlPO4/ZrO2=3) systems obtained with ethylene oxide and subjected to different stages of heat treatment has been studied through the irreversible adsorption of organic bases and benzoic acid. The decrease in the amount of acid sites as calcination increases is consistent with the decrease in Bronsted acidity, as shown by the decrease in O−H band intensity. Infrared spectra show Td symmetry in which the phosphorus atom is surrounded by the tetrahedra of oxygen atoms.

Skeletal isomerization of cyclohexene to 1- and 3-methylcyclopentenes has been carried out at temperatures ranging from 250–400 °C using a microcatalytic pulse technique, over AlPO4 catalysts having various amounts of alkali cations (1–5 wt.%, Li, Na and K). Apparent rate constants and activation energies were calculated in terms of Bassett and Habgood's kinetic model for first order processes in which the surface reaction is the controlling step and partial pressure of the reactant is low. The results show that alkali-containing catalysts exhibit lower activity and higher selectivity to 1-methylcyclopentene than pure AlPO4 due to the modification of the surface acidity by alkali impregnation.