摘要:
Diene rubber compositions are described containing a diene elastomer, a reinforcing inorganic filler, and a coupling agent wherein the inorganic filler includes a silica having the following characteristics: (a) a BET specific surface area between 45 and 400 m2/g; (b) a CTAB specific surface area between 40 and 380 m2/g; (c) an average particle size (by mass), dw, of 20 to 300 nm; and at least one of the following characteristics, preferably two and more preferably all three: (d) a particle size distribution such that dw≧/CTAB)−30; (e) a porosity which meets the criterion L/FI≧−0.0025 CTAB+0.85; (f) an amount of silanols per unit of surface area, NSiOH/nm2; NSiOH/nm2≦−0.027 CTAB+10.5. These diene rubber compositions can be used for the manufacture of tires or of semi-finished products intended for tires.
摘要:
The invention relates to a novel method of preparing silicas and to highly-structured silicas having the following characteristics: a specific surface area CTAB (SCTAB) of between 40 and 525 m2/g; a specific surface area BET (SBET) of between 45 and 550 m2/g; an object size distribution width Ld ((d84−d16)/d50), which is measured by XDC particle size analysis after deagglomeration with ultrasound, of at least 0.91; and a pore-size distribution such that ratio V(d5−d50)/V(d5−d100) is at least 0.66. The invention also relates to the use of said silicas as polymer reinforcing fillers.
摘要:
A dispersion includes an apolar organic phase, at least one amphiphilic agent, and solid objects based on particles of an iron compound in crystallized form of small size.
摘要:
The invention relates to a method for treating a gas containing nitrogen oxides (NOx), in which an NOx-reduction reaction is carried out using a nitrogen-containing reducing agent, which invention is characterized in that the catalyst used for the reduction reaction is a catalytic system containing a composition comprising zirconium, cerium and niobium in the following percentages by weight, expressed in terms of the weight of oxide: 10-50% of cerium, 5-20% of niobium and the remainder consisting of zirconium.
摘要:
A method is described for treating a gas including nitrogen oxides (NOx). The method can include conducting a reduction reaction of the nitrogen oxides with a nitrogen reducing agent. Further described, is a catalyst used for the reduction reaction which is a catalytic system including a composition based on cerium oxide and including niobium oxide in a proportion by a mass of from 2% to 20%.
摘要:
A composition based on cerium, zirconium and tungsten is described. The composition has a content expressed as an oxide, of which cerium is from 5% to 30% of the composition, tungsten is from 2% to 17% of the composition, and the remainder of the composition is zirconium. After aging at 750° C. under an air atmosphere including 10% water, it has a two-phase crystallographic structure having a tetragonal zirconia phase and a monoclinic zirconia phase, with no presence of a crystalline phase including tungsten. The composition can be used as a catalyst, especially in an SCR process.
摘要:
A dispersion includes an apolar organic phase, at least one amphiphilic agent, and solid objects based on particles of an iron compound in crystallized form of small size.
摘要:
A composition is described that includes oxides of zirconium, cerium and another rare earth different from cerium, having a cerium oxide content not exceeding 50 wt % and, after calcination at 1000° C. for 6 hours, a maximal reducibility temperature not exceeding 500° C. and a specific surface of at least 45 m2/g. The composition can be prepared according to a method that includes continuously reacting a mixture that includes compounds of zirconium, cerium and another rare earth having a basic compound for a residence time not exceeding 100 milliseconds, wherein the precipitate is heated and contacted with a surfactant before calcination.
摘要:
The invention concerns a method for preparing anisotropic silica aggregates comprising the following steps: a) contacting at least one polymer with non-aggregated silica particles and/or highly dispersed in an aqueous medium, with a ratio R, polymer weight to silica particle surface, ranging between 0.03 and 2 mg/m; 2; and whereof the electrostatic value of the silica particle surface is not less than the value of the charge of the silica particle surface measured in an aqueous phase without added salts at a pH not less than 7; b) consolidating the aggregates obtained at step a) either by heat treatment, or by precipitation of a mineral compound. The invention also concerns a silica aggregate comprising a chaining of elementary particles whereof the number of particles ranges between 5 and 15, whereof 80% of elementary particles are in contact with not more than 2 particles and whereof the greatest distance measurable between 2 points of the aggregate is not more than 5 times the average size of one elementary particle.
摘要翻译:本发明涉及一种制备各向异性二氧化硅聚集体的方法,包括以下步骤:a)使至少一种聚合物与非聚集的二氧化硅颗粒接触和/或高度分散在水性介质中,R与聚合物重量与二氧化硅颗粒表面的比率, 范围在0.03至2mg / m; 2; 并且二氧化硅颗粒表面的静电值不小于在不低于7的pH下在没有添加盐的情况下在水相中测量的二氧化硅颗粒表面的电荷的值; b)通过热处理或通过沉淀矿物化合物来固化在步骤a)获得的聚集体。 本发明还涉及一种二氧化硅聚集体,其包含基本粒子的连接,其中粒子数目在5至15之间,其中80%的基本粒子与不超过2个粒子接触,并且其中2个点之间的最大距离可以测量 聚集体不超过一个基本粒子的平均尺寸的5倍。
摘要:
A composition is described that includes a perovskite of the formula LaMO3, where M is at least one element selected from among iron, aluminum or manganese, in the form of particles dispersed on an alumina or aluminum oxyhydroxide substrate, wherein after calcination at 700° C. for 4 hours, the perovskite is in the form of a pure crystallographic phase, and in that the size of the perovskite particles does not exceed 15 nm. The described composition can be used in the field of catalysis.