抗有机杂质镀镍添加剂对阴极极化性能的影响

研究了有机杂质以及抗有机杂质添加剂对镀镍过程中阴极极化性能的影响．实验结果表明，有机杂质增大了阴极极化，而抗有机杂质添加剂却能减小阴极极化．实验结果还显示，添加剂消除有机杂质污染的效果同其降低阴极极化的能力密切相关     

The projection operator approach to the Fokker-Planck equation. II. Dichotomic and nonlinear Gaussian noise

Two models for the Freedericksz transition in a fluctuating magnetic field are considered: one is based on a dichotomic and the other on a nonlinear Gaussian noise. Both noises are characterized by a finite correlation time. It is shown that the linear response assumption leading to the best Fokker-Planck approximation in the dichotomic and nonlinear Gaussian cases can be trusted only up to the order ¹ and ⁰, respectively. The role of the corrections to the linear response approximation is discussed and it is shown how to replace the non-Fokker-Planck terms stemming from these corrections with equivalent terms of standard type. This technique is shown to produce perfect agreement with the exact analytical results (dichotomic noise) and to satisfactorily fit the results of analog simulation (nonlinear Gaussian noise).     

The projection approach to the Fokker-Planck equation. I. Colored Gaussian noise

It is shown that the Fokker-Planck operator can be derived via a projection-perturbation approach, using the repartition of a more detailed operator into a perturbation ₁ and an unperturbed part ₀. The standard Fokker-Planck structure is recovered at the second order in ₁, whereas the perturbation terms of higher order are shown to provoke the breakdown of this structure. To get rid of these higher order terms, a key approximation, local linearization (LL), is made. In general, to evaluate at the second order in ₁ the exact expression of the diffusion coefficient which simulates the influence of a Gaussian noise with a finite correlation time, a resummation up to infinite order in must be carried out, leading to what other authors call the best Fokker-Planck approximation (BFPA). It is shown that, due to the role of terms of higher order in ₁, the BFPA leads to predictions on the equilibrium distributions that are reliable only up to the first order in t. The LL, on the contrary, in addition to making the influence of terms of higher order in ₁ vanish, results in a simple analytical expression for the term of second order that is formally coincident with the complete resummation over all the orders in t provided by the Fox theory. The corresponding diffusion coefficient in turn is shown to lead in the limiting case to exact results for the steady-state distributions. Therefore, over the whole range 0 the LL turns out to be an approximation much more accurate than the global linearization proposed by other authors for the same purpose of making the terms of higher order in ₁ vanish. In the short- region the LL leads to results virtually coincident with those of the BFPA. In the large- region the LL is a more accurate approximation than the BFPA itself. These theoretical arguments are supported by the results of both analog and digital simulation.     

CuO—ZnO／Al2O3—TiO2催化剂中TiO2的结构和电子效应

采用XPS,XRD,TPR,TPD和指标反应等方法研究了TiO_2在负载型CuO-ZnO/Al_2O_3-TiO_2催化剂中所起的作用.发现TiO_2起双重作用,即结构效应和电子效应,TiO_2的结构效应主要表现为它改善了CuO在载体上的分布.TiO_2的电子效应表现为它对Cu~0具有吸电子的作用,从而削弱了Cu和S之间的吸附力,使S容易脱除.另外,部分还原形成的Ti~(3+)具有促进CuS中的Cu~(2+)还原为Cu~0的能力,TiO_2的上述效应的综合结果使催化剂的抗硫中毒性能大大增强.     

催化裂化USY／ZnO／Al2O3脱硫添加剂的高温水热失活

 对USY／ZnO／Al2O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察，发现老化后添加剂的脱硫性能大幅度下降．采用XRD和IR等技术对USY／ZnO／Al2O3添加剂在高温和高温水热条件下失活的原因进行了研究．结果表明，在高温下，ZnO可与USY沸石中的铝发生固相反应生成ZnAl2O4尖晶石，从而造成USY晶体结构崩塌，转变成无定形状态．在ZnO含量较高的条件下，ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应，生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构．这一方面使添加剂失去了可形成硫化物吸附中心的ZnO，另一方面破坏了硫化物的裂化活性组分USY，从而造成添加剂脱硫性能下降甚至失去脱硫活性．ZnO对USY的破坏作用主要与温度有关．在USY／ZnO／Al2O3体系中，ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离，单纯的高温条件对添加剂的破坏不显著，而水蒸气可以促进ZnO的移动，有利于ZnO与USY的接触，因此在高温和有水蒸气存 在的条件下添加剂的结构易遭到破坏．     

新型柴油节能降污添加剂的研制

为改善柴油燃料的燃烧性能,充分利用有限的石油资源,通过对两种单剂的制备、筛选,研制了一种新型柴油节能降污表面修饰纳米添加剂 添加剂以0.01‰质量分数加入柴油中,能显著提高柴油的燃烧效率、减少残炭.     

催化裂化汽油脱硫添加剂USY/ZnO/Al2O3的性能评价

 在固定流化床催化裂化装置上，以减压蜡油为原料，对制备的U\r\nSY／ZnO／Al2O3催化裂化汽油脱硫添加剂的性能进行了评价．结果表明\r\n，随着添加剂添加量和剂油比的增加，生成汽油的硫含量降低．在500\r\n℃和剂油比为5的条件下，在FCC平衡催化剂中添加30％的添加剂时，汽\r\n油的硫含量可由不加添加剂时的1230μg／g降低到770μg／g左右．添\r\n加剂的添加量（10％）较低时，对催化裂化产物的分布基本没有影响；\r\n添加30％的添加剂时，焦炭的产率有所增加，但汽油收率基本不变．X\r\nRD表征结果表明，USY／ZnO／Al2O3添加剂中的ZnO对USY的晶相结构有\r\n一定的破坏作用，但随着反应与再生次数的增多，ZnO与Al2O3之间形成\r\n较为稳定的锌铝尖晶石结构，使添加剂的性能趋于稳定．     

Statistical replacement for systems with delta-correlated fluctuations

Nonlinear systems with stochastic parameters are approximated by simpler systems using a method that we call statistical replacement. This method is an extension of the previously developed AGREE which was restricted to systems with additive fluctuations. Statistical replacement incorporates the distinctions between globally stable thermodynamically closed systems and thermodynamically open systems that can be unstable.